Make it clear regarding rectangle copy/paste I would still use it only in Geany. Not over multiple applications.
I would believe that over multiple apps in MAC OS could be an issue... But only the first part of the string is copied from the terminal and then all modifications including block copy paste are in the same list...
The trouble is that using a different character like `\1` to indicate block copy introduces side effects and I don't think Neil (the maintainer of Scintilla) would accept such a fix.