On the first point, I am definitely inclined to agree, it would be nice if there were some additional dynamics involved with the parts between the bosses, if some trash actually had mechanics, especially the filler trash, e.g., NOT the Apa which you need to burn down, or let live, depending.

I don't mind the second point of this for Variant (Normal ver.) since they are to a degree meant to act as a sort of 'vehicle' for exploring the dungeon, rather than something to burn through.

It would be nice if the first boss had more variance, or if each separate route had a separate first boss. There's not a great enough variance between mechanics and 'design' for it to really be impactful at all.

A greater number of lost actions would be nice, but then in the same vein if it changes job dynamic, e.g., how you might play a particular job. But anything further is... It would feel like the encounters need to then be designed around having a certain set of actions - Either that or they just are inconsequential.

Delubrum Normal was fun the first time that was all. Trinity Avowed was a nice boss with the Hot & Cold mechanic. But otherwise it got very boring and uninteresting after a few turns. I wouldn't really call Delubrum any more or less interesting than Variant, frankly - But different strokes for different folks.

It would be nice if they could cycle their content a bit more, rather than having this expansion as, say, exclusively variant dungeons, cycle it so it has a variant/criterion, and then a large-scale raid like Delubrum and then back to Criterion/Variant, just to give themselves a chance to actually reflect on how to make the content better without it needing to span several expansions like always. - They do have a habit of finding something new and 'innovative' and then spamming it over and over.