I loved that you managed to get the boys down again today after they did that cat nap in the buggy at 11am. Well done you!
You know, I know that you are leaning towards consolidating the two naps into one longer one but before you do that I just wondered if you'd think again? But please take any thoughts I share with a pinch of salt if you need to because you know the boys better than anyone and that is what this forum is for... To take what you might find useful and discard what you don't

Can we clarify what an under tired vs overtired nap actually is? I have always gone with the notion that an overtired nap is 30 mins and an under tired nap is 45 mins. Given this, I think that the boys might actually be having an overtired nap in the morning and that if you bought it significantly earlier (to 8.30/8.45) then it would lengthen to 45 mins. This would be much more restorative for them than 30 mins and I think they'd then consistently do a longer pm nap, which you could also bring earlier (as you wanted to do anyway) thus allowing plenty of awake time before bed, with them having had enough daytime sleep to avoid overtired and more frequent night wakings. I also think this might help extend the morning wake up times. And it would give you slightly more time in the middle of the day to run errands etc.
With feeds... Are they still taking full bottles four times a day? If so I would leave it as four but if the middle two are starting to reduce then that is what I would consolidate rather than the naps. So perhaps do wake up feed, one at 12.00 then bed time feed??
I sincerely hope you are in the middle of a deep sleep right now given that it's 1am over there, and that the rest of the night isn't too traumatic!