Well that was waste of a day (due to OC changes in r5123+ changes)... the problem I had was I had thought I had backed up the EFI directory, but I had only to the 'master' volume. Just took ages to get get a new bootable USB together. Anyway... all good now! I suppose it time to gen-up on the OpenCore... maybe my next machine needs to be Ryzen based!
Updated also my second and last Hackintosh GA-H61N-USB3 + i5 + GT640. Same as the first Hackintosh (combo update from 10.15.2 to 10.15.7 and then supplemental from Apple Store). No problems with the usual two shutdowns and restart. Also no need to reload the audio kext. And so my dear friends here I am at the end of this incredible experience (all started in 2008 buying in few months parts for two Hackintoshes. It was sooo exiting). I will probably try to instal Big Sur but if I cannot (I have very old machines) I will enjoy these computers for sometime (two-three years?) with Catalina. Maybe a stupid question: is this the last update for Catalina? To be honest I hope yes. One more question; I lost the possibility of sign as a guest. Is this normal?