From my conversation with Christoph, he did all of the programming in assembly language.
This is probably true only for DSP part. If you look at crash logs / stack traces and diagnostics files many files are C/C++ headers, many functions are in Access:: namespace (maybe still remembering Virus times?), internally KPA uses sqlite as a storage for presets, profiles (embedded db, written in pure C). And KPA runs on top of some operating system (on ARM-based CPU), with sys calls, which would indicate that there is kernel / user space separation.