The boost is all over the place according to your app. Can't be very pleasant to drive like that! A huge boost spike is typical of a Revo map but other mappers like the more aggressive approach also.
You can tell if it's been remapped with VCDS, by looking at a byte called "Flash count". Standard should be zero and every time the ECU gets flashed (remap), the count goes up by 1. You can't tell what's actually been done to the map without special software because remappers encrypt their code.
VCDS is the way to go. You can data log many sensors and output them into a pretty Excel graph. Where are you based? I'm sure someone with VCDS is pretty close to you.
I would initially data log:-
Requested boost pressure
Actual boost pressure
Mass Air flow (do a hard pull to the redline in 4th, or 3rd if you don't have the road space)
Requested fuel rail pressure
Actual fuel rail pressure
From those things we can quickly see if it's been remapped.
Standard boost is 0.9 bar and VCDS is metric, and the MAP sensor is upstream of the intake, so will not record vacuum (inHg).
Standard rail pressure never exceeds 115 bar, so if you're seeing 120+, it's definitely mapped.
And finally, divide your peak MAF reading by 0.8 to get a very close approximation of BHP.
Does your app record fault codes? A faulty N75 valve can cause an overboost condition and a broken PCV and / or dump valve can cause an underboost condition. That's why VCDS is great because you can compare requested to actual to see how far adrift things are.
So yeah, buy yourself VCDS! The best forensic tool for VWs out there