ME7 ECU work with LSU 4.9 without problems, so this ECU should work with LSU 4.2, but for safety is easier to mount LSu 4.9 and be sure

Can you explain me what is so special about that ECU?
At the end did you made any logger working?

As the boot mode, when I was working with me 7.1.1 from 4F 4.2 N/A  I connected cable to boot pin, and flashed ECU with galleto 1260, it takes about 2 minutes what  is not big difference when nefmoto take 1+ minute

Also for logging, I was having two ECUs one was 4F0 910 560 0030, other same part number only have letter at end. From same care same engine code only 1 year difference. One was able to logging with me7logger (this older) second could not connect.  I can find both bin files if that help,  I don't know where to search about that logging stuff in IDA to compare it