Dave
Honorary Master
https://www.sammobile.com/forum/showthread.php?t=37112
Read the disclaimer again, and do your own research.
Makes no sense, I've often flashed Samsungs to totally new CSC's (and back again) not in the original grouping without issue. Why would it be any different?
I suspect you are reading more into it than there is, TBH, your whole post doesn't sound very different to how you flash with Odin on any Samsung...
I have an S7, originally on Vodafone, unique CSC of VOD, I've flashed it to BTU (BTU, CPW, DBT, ITV, KOR, NEE, XEF, XEO, XEU), I've then flashed it to H3G and then back to BTU, and then to XEU, back to BTU, then to O2U and back to BTU, and then finally to EVR and eventually back to BTU.
as long as you flash all 4 files and use the CSC file (so it wipes the phone) it has always been ok.
My S8 is staying very far way a from any water.