So I've now run all three of the dungeons of Dawntrail's expert roulette.
If you haven't yet run all three or you're not anywhere near these level 100 dungeons, please stop reading now...and go back to MSQ.
So. The first of the three took me several attempts to clear, on duty support (because it was late and the server was relatively empty).
In the Alexandria dungeon, the first boss is quite literally the make or break encounter of the dungeon. After now running it a second time...this time with real people, even knowing the mechanics ahead of time did not make it easier.
What do I mean?
well the boss has 4 different types of AoEs that it uses, split apart two (or three if you want to be technical about it) different mechanics.
The first - where the boss is "charging up" to fire a coned blast forward or to the sides
The second mechanic - the + or O symbols it creates around it as part of dispersing intruders.
So in my experience, its the second one that needs refinement or a little adjustment.
So for the second mechanic it takes little time to learn what to do (either stand inside the O or stand in the area near the + that isn't getting blasted by the AoE).
The problem is that as far as timing goes, there is probably a couple seconds of cooldown between when the previous symbol "blows" and when the next one goes off. Simply put you have to either be positioned ahead of time to be able to anticipate the next AoE, or you are about 90% certain to get the debuff. In my first couple attempts of it (I main PLD fyi), it was extremely difficult to get to get the timing down even despite knowing what to do. Even after successfully completing the dungeon once before, it was a struggle a second time (even with real people instead of NPCs for this run).
My suggestion (although clearly take with a grain of salt, as I'm just one player) would be extend the timers between AoEs by another couple seconds.
Additionally, if the boss using both mechanics simultaneously (charged frontal cone or charged sides cone in addition to the symbols) is intentional...then that is a separate concern, as that makes trying to dodge the symbol AoEs even more difficult than it already is.