@Arnaud (https://www.cpcwiki.eu/forum/index.php?action=profile;u=1424) (the creator of many awesome games!) kindly made a tutorial to easily use the Arkos Tracker 2 player into CPCTelera (for both music and sound effects).
The French version can be found on the AT2 website (http://www.julien-nevo.com/arkostracker/index.php/using-cpctelera-with-at2/), and the English version on the essential 64 NOPS (https://64nops.wordpress.com/2020/12/20/easy-integration-of-arkos-tracker-2-player-with-cpctelera/) tech blog.
Thanks again Arnaud for your great work!