I have read that Discord channel discussion before the flash and it seems that the person who tried it (sorgo) did it few months ago, so it could actually work on that slightly older Lineage version, or maybe he did some additional or different steps back then, I don't know. I'm back on Lineage, restored backup (Swift Backup with root FTW! 😉 ) and nearly everything is as before with the touchscreen working as it should, finally.