Having had some issues getting down to the what do I need for X and thus how to find that amount of Y. I knew my answer was mostly "easily" found by stepping back in the News entries on the main PSO2 site. Vs. navigating the many threads where things like Schvelle Boosters, Ultimate Boosters, etc. are mentioned. But not exactly on WHERE or HOW to obtain them.
https://pso2.com/news/announcements/star15weapons
For all the How do I get, where do I get, find obtain X booster/whatever its called questions out there. And maybe this will be of help for something more current not mentioned on the link.
Fwiw.
o/ =^.^=