Please provide the mileage, year, and model of your vehicle. That's very important...

STFT and LTFT should be between -10% to 10% where 0% is perfect (and desired). Positive fuel trims mean that fuel is being added to compensate for a lean mixture, and negative fuel trims mean that fuel is being subtracted to compensate for a rich mixture. STFT are the instantaneous changes to the mixture while LTFT are the changes being made longterm (how the engine is running overall). 

Lambda is the air-fuel mixture reading. So when lambda = 1, the air-fuel mixture is at a proper 14.7:1 (stoichiometric mixture of 14.7 parts of air per 1 part of fuel). Then lambda <1 is rich and lambda >1 is lean. 

I'm not sure where you got that 0.50-0.90 for fuel trims. Fuel trims are given as percents and O2 sensor data is given in volts so 1V means a perfect mixture (this is never a steady 1V, it should be hovering close to 1). When providing data, please state what it is and give the units as well (V, psi, lb/min, etc.)

That last code P0420 is for an inefficient catalyst, which is why I ask for mileage.

Look at the freeze frame data from when the codes were thrown.

See what the sensors were reporting at that time.

It will tell you if this happened at idle or higher rpms. What the engine temp was.  What the fuel trims were doing. Your intake air temperature. Throttle position. What your O2 sensors were reporting.

If it's an intermittent problem your live data won't show it.

As far as MAF, a "loose" rule of thumb on a MAF's air flow rate at idle is 1 gram per second per liter of engine displacement.

So if you have a 2.0 Liter engine, you'd expect your MAF to read around 2g/s at idle (plus or minus a little is fine)

Some obd2 scanners will report MAF in Lbs/s so don't be fooled.

It could be normal depending upon the engine rpms when the code was thrown as MAF will be relative to engine rpms. For your 3.5 L Accord the MAF should read around 3 to 4 g/s  at idle.

It will increase as rpms increase because the MAF measures air intake into the throttle body. in the case of reading your freeze frame data you want to reconcile MAF to RPMs at the time.

Your MAF voltage and airflow doesn't appear that the code was thrown during idle, or I should say that the MAF value is too high for idle.

Having both P0172 and P0175 codes means that the  the lean condition existed on both cylinder head banks when the code was thrown.

So I'd rule out intake manifold gaskets leaking because having both intake manifold gaskets fail on both banks at the same time is unlikely to say the least.

Since you aren't complaining about any other driveability issues that seems to point to either a vacuum leak or the MAF reporting more airflow than is actually occurring.

If you had fuel pressure problems you'd be complaining about your Accord running poorly.

So either the  Mass Air Flow Sensor is telling the computer that much more air is entering the engine than actually is, or you have a vacuum leak where air is sneaking into the intake manifold downstream of the MAF sensor.

Either way, based on the "dubiously inflated reporting" of the  amount of air entering the engine from the MAF sensor, or a vacuum leak, , the engine computer or PCM is spraying more fuel into the combustion chambers.

Meanwhile, the upstream oxygen sensors are telling the computer that the engine is running too rich and that  less fuel is needed.  The computer tries  to compensate, but since the MAF is saying one thing and the upstream O2 sensor is saying another,  resolution is impossible, it sets the code

Your P0420 code will resolve itself when you correct this condition.

Bottom line, I'd spray some brake cleaner or carb cleaner around vacuum lines and connections to find any leaks if they exist. (Idle will increase if you spray a vacuum leak.)

if you don't find any, replace the MAF sensor

Yeah, I owe you an apology. I re-read that last post after I posted it and I thought, I'm going to confuse the hell out of this guy. I tried to edit it, but the time to edit it had expired.

It isn't you, it's me.

I'll try again.

It appears the MAF sensor is over-reporting the amount of air being sucked into the intake.

So the computer, using that "inflated" reading, is adding what it thinks is the appropriate amount of fuel to maintain a 14.7:1 air/fuel ratio.

Meanwhile, both upstream O2 sensors are correctly reading the mixture as too rich at the exhaust and they're  telling the computer to lean the fuel mixture. (negative fuel trims)

So you (rightly)  expected to see negative fuel trims in your freeze frame data from when the codes were thrown.

So, it's not a vacuum leak because the MAF sensor wouldn't be reporting those to the computer and the upstream O2 sensors would be reading a lean mixture, not a rich mixture.

It's not a fuel delivery issue (fuel pump, fuel filter, fuel pressure regulator) because  the upstream O2 sensors would, again, be reading a lean mixture if one of those were failing. (unless an injector was leaking but you have "too rich" codes on both cylinder banks, P0172 (too rich bank 1) and P0175 (too rich bank 2) and it's unlikely that 2 injectors on opposite sides of the engine started leaking at the same time.

So the MAF sensor becomes the "leading suspect".

I know when this stuff is new to people it's hard enough to "wrap their heads around it" without being offered confusing explanations like my last post, and again, please accept my apology.

I wish there was a way to create a table here, here is some live data. I think this is during the car's "close loop" cycle, because I started recording well after the car was warm, and after driving it around for ~10 mins.

RPM  | AF Sensor B1 (mA) | AF Sensor B2 (mA) | HO2S B1 S2 (v) | HO2S B2 S2 (v) | STFT B1 | LTFT B1 | STFT B2 | LTFT B2 | MAF (v) | MAF (g/s)
1015    | 0.06                           | 0.09                             | 0.31                     | 0.76                     | 0.73        | 0.81        | 0.73         | 0.80       | 1.55         | 9.28
1763 | 0.07                      | 0.07                      | 0.10                 | 0.08                  | 0.78      | 0.81      | 0.78       | 0.80      | 2.37      | 32.23
2517 | -0.11                     | -0.03                     | 0.76                 | 0.65                  | 0.77      | 0.81      | 0.77       | 0.80      | 2.65     | 45.36
2602 | -0.43                     | -0.44                     | 0.76                 | 0.65                  | 0.75      | 0.81      | 0.75       | 0.80      | 1.75     | 13.47
1920 | -0.18                     | -0.09                     | 0.80                 | 0.82                  | 0.73      | 0.81      | 0.73       | 0.80      | 1.76     | 14.17
1756 | -0.65                     | -0.56                     | 0.84                 | 0.82                  | 1.00      | 0.81      | 1.00       | 0.80      | 1.63     | 10.56
1272 | 3.81                      | 3.49                      | 0.00                 | 0.00                  | 1.00      | 0.81      | 1.00       | 0.80      | 1.41     | 6.96
1157 | 0.12                      | 0.14                      | 0.10                 | 0.65                  | 0.73      | 0.81      | 0.73       | 0.80      | 2.25     | 28.41
1972 | 0.05                      | -0.03                     | 0.10                 | 0.56                  | 0.76      | 0.81      | 0.77       | 0.80      | 2.53     | 38.69
2475 | -0.02                     | -0.00                     | 0.75                 | 0.67                  | 0.77      | 0.81      | 0.76       | 0.80      | 2.76     | 51.95
2934 | -0.14                     | 0.07                      | 0.78                 | 0.61                  | 0.74      | 0.81      | 0.73       | 0.80      | 2.84     | 56.88
2264 | -0.78                     | -0.68                     | 0.84                 | 0.73                  | 0.73      | 0.81      | 0.73       | 0.80      | 1.75     | 11.58

Hopefully I Measured all the important sensor readings. If I've missed some, please let me know.

Update: 

I cleaned the MAF sensor and don't think that will make any difference. I'm getting the same readings