Bulk Rename Utility

I want to rename some of my files, but not sure how I can accomplish.

Here is the items I am trying to rename

test1
test1 (track2)
test1 (track3)
test2
test2 (track2)
test2 (track3)
test2 (track4)

I want to rename above items so it would look like this below

test1 (track1)
test1 (track2)
test1 (track3)
test2 (track1)
test2 (track2)
test2 (track3)
test2 (track4)

How would I accomplish this?

This 1Regex matches filenames not ending with ) and appends them with (track1)
(.*[^)])$
\1 (track1)

Without knowing more filename details, its hard to include any more filtering
Just be careful when selecting files, as anything not ending with ) can get appended