Below are 2 walkthrough's, a gamefaqs forum, an rpg shrine, and a google document.

http://tartarus.rpgclassics.com/secretstars/

https://retromaggedon.com/index.php/tecmo-secret-of-the-stars-snes-walkthrough/

http://www.geocities.ws/dustydimondbball/Secret.txt

https://gamefaqs.gamespot.com/boards/588647-tecmo-secret-of-the-stars/63681715

https://docs.google.com/spreadsheets/d/1rYf4DpLB6XRgO-peJD6U0KmfDMIfbHuEsHKOuStMepM/edit?pli=1#gid=1616871558