Example cue file:

REM DATE 2021-08-14 04:27 PM
REM RECORDED_BY "rekordbox-dj"
TITLE "My Mix"
PERFORMER "DJ Me"
FILE "My Mixfile.wav" WAVE
	TRACK 01 AUDIO
		FILE "c:/path/to/artist1-song1.mp3" WAVE
		TITLE "Song One"
		PERFORMER "Artist One"
		INDEX 01 01:00:00:00
	TRACK 02 AUDIO
		FILE "c:/path/to/artist2-song2.mp3" WAVE
		TITLE "Song Two"
		INDEX 01 00:22:41:00
	TRACK 03 AUDIO
		FILE "c:/path/to/artist3-song3.mp3" WAVE
		PERFORMER "Artist Three"
		INDEX 01 01:08:15

Rekordbox produces a non-standard CUE file in that it uses hh:mm:ss:ff in the INDEX. The standard is mm:ss:ff; however, this abnormality is handled correctly.

Tracks 01 and 02 use this non-standard INDEX. Track 03 is standard.

Note that PERFORMER has been removed from track 02, and TITLE from track 03. This is only to illustrate how those missing records are handled.

Resulting label file:

3600.000000	3600.000000	Song One (Artist One) [c:/path/to/artist1-song1.mp3] 
1361.000000	1361.000000	Song Two (My Mix) [c:/path/to/artist2-song2.mp3] 
68.200000	68.200000	My Mix (Artist Three) [c:/path/to/artist3-song3.mp3]

Note that in track two the missing performer has been filled in with the main performer.

Similarly, in track three the missing title has been filled in with the main title.

The non-standard indexes of tracks 01 and 02 have been properly parsed. And of course the standard index of track 03 is not an issue either.

General Notes

Without a doubt, some new non-standard CUE file will appear. Or there will be a request to somehow get other CUE file attributes into the label file. There's a fair probability that I will address the former, but little chance I will pursue the latter.