Lets discuss KFLDHBN in ME7. I have seen different tables in RS4 B5, BAM 1.8T and APX 1.8T files. Why did the engineers bother to change them if they are not addressed at stock levels (lets say max 2.2). I am curious. The first is the APX which reduces heavily at temps lower than 30deg IAT. Why?

It protects turbo from overspeeding at high IAT by limiting max boost request.

As to why the APX & BAM are different; probably hardware differences/limitations
despite them being mostly identical  

But you are going to be between 20℃ & 70℃ on IAT in most cases,
and in that range the is little to no difference between the two.

No, because ME7 is load based you need to look at load input. If the mass air intake is lower, the ecu will request more duty from the turbo to achieve requested load. In result your turbo will have higher shaft speeds/pressure for the same mass flow. KFLDHBN is for turbo protection when going on high altitude, when the air gets thinner. It is not boost pressure but pressure ratio between ambient pressure and turbo outlet pressure. You can look at the k04 compressor map and verify max pr.
Why the BAM has different low temp values than the APX, I dont know. I would just match them to the highest values in the corresponding rpm column or calculate max pr that keeps you on the compressor map at those engine speeds and use that.