Interesting thread you’ve started
@Jackel.
From what I’ve read in other threads, the simplest thing to try when one has an issue with their auto is to do a fluid change and with that may as well do a deep pan and wide mouth filter upgrade.
As for the rest being too technical, same for me here, but have a read of GMs install guide
here which may help to improve some basic understanding of a trans swap and what is needed. The linked doc is for VE 6L80 trans but it may be relevant to our VFs. What may be especially interesting is the references to correct fluid level, battery, maf and tps as well as to trans relearn but for you the most interesting is that GM state ECU and TCM are programmed together. The implication is that there is some dependency between ECU and TCM which if true would mean you’d loose your custom flash if you went to Holden service as they may want to reflash the trans... How a tuner doesn’t impact the TCM when flashing ECU I don’t know... others here would know so I may learn a little