I had another idea. All the live performances file names end in "-xx]"
Is that something syntax could be used for to make it to "-19xx]"?
You only want to change the filenames?
Select the tracks that end in "-xx]" > right-click > File Operations > Rename to > select '...' and enter -
$insert(%filename%,19,$sub($len(%filename%),3))
^ This inserts 19 at 3 characters from the right.
Edit: Alternatively for either century...
$insert(%filename%,$ifgreater($num($right(%filename%,3),2),31,19,20),$sub($len(%filename%),3))
^ This tests "xx" and inserts 19 (if >31) or 20 (if <31) at 3 characters from the right. I think it should work for either century but always check the preview first.
The idea kode54 posted would work for tags except you needed more steps and having the steps in the correct order that was mentioned. Did you want to fix tags as well?
You can just copy filename to title if the above is sufficient - right-click tracks > Properties > Tools button > Automatically Fill Values > enter Pattern -
%%. %title%
^ If filename is "01. Get Back (01-12-2002)", title becomes "Get Back (01-12-2002)"