Guess I don't understand what mechanics you are struggling to understand?
Because you didn't set it up, someone else told you what to do and organized everything.
It would be like asking the GEO how to kill Ongo and them replying "cast bubbles, SC and git gud".
So to actual mechanics. We think Cleansing Bubbles is not a TP move but on a timer. One time we used Absorb-TP every 8~9s and it was always 0, and she still used Bubbles, but the timer seems to now be linked to Silence landing. The mobs still get a 15% HP regen every 3s but seem to be more vulnerable to SC damage. Spinning Fin sucks, so thunder resistance is recommended, maybe even using a bard song slot for it. If bubbles is only used after silence, then we can gather in the middle and nitro sleep should last the entire fight and now the respawning mobs don't have any status ailment resistance built-up either.
That is why I asked you about Bubbles, and your response told me you have no idea about the fight and just played a single role.