Yes, StringReplace as well. (Although in AHK v2 you can write every command as a function, and every function as a command. So ... the StrReplace command in AHK v2, is quite similar to the current StringReplace command.)
I wouldn't worry too much about conversion, I've converted lots of code/scripts, you just need a good converter, me and others are working on it. The vast majority of conversion can be automated, by converting certain command/function lines, and then inspecting the before/after results in WinMerge, to see that everything has converted successfully.
However, I think it's worth checking the changes, to avoid writing any new code that is awkward to convert, for me, that basically means avoid using multiple parameters on a Return line.
Btw SetFormat is due to be removed, personally I never use it, but you have used it a few times in your script, so you may want to look at the Format function.