@dolik-rce not forgotten, this was the next thing I planned to test after Scintilla 5 updates if nobody beat me to it. Due to Scintilla being central to Geany and this update being a jump of two major versions of Scintilla it is important to do first to allow maximum testing. Unfortunately there have been a couple of bugs in Scintilla which are addressed in 5.1.4 due out "in a couple of days" and should allow that to be merged.
Of course that doesn't stop anyone else from looking at this and/or updating to the latest ctags as discussed above.