my subtiles has colons and semi colons as part of the displayed text, is there any program that will specifically target the ones in the tc?
I didn't find one in a quick search. Certainly doable, but would need the equivalent of programming. Import into Excel, isolate the timecode columns, replace only within those columns while ignoring the lines with only text.
If you don't find a tool like that, compare the time to create such with recreating the subs in subtitle edit, or a replace (in notepad) where you have to confirm every instance.