As just a pure conjecture theory I think you could maybe come up with something plausible like, even with the machinations of the Ascians, the conditions for a calamity aren't completely in their control and there's all sorts of timing issues with regards to aetherial and temporal alignments that they have limited/no power over. So they have no way of knowing when the next opportunity for a calamity will arise which is why they typically take thousands of years. So having an opportunity present itself just 5 years after the previous calamity was an insane stroke of luck and too good to pass up, so they just had to try and take their chances and work around the WoL.
That's just me spitballing a reasonable explanation though, it's based on absolutely nothing. I dunno if it even completely jives with the lore since they seem to be trying to cause multiple different kinds of calamities one after another each time they're thwarted. I'd be really surprised if in Endwalker they manage to give a solid explanation that actually ties into the narrative, like we learn that they're working on a time limit that they've only recently discovered or something which is why they're now desperately accelerating.
I quite like this explanation actually. The idea of a Darkness primal who seeks balance with Light does feel kind of "off" in some respects, but there's precedent for primals that are selfless (or at least not entirely selfish) to some degree. If we think of Zodiark as a primal of salvation and restoration then Elidibus' preoccupation with balance does make a bit more sense, if we're assuming that he doesn't just say that to trick people.
Although, if we assume that Elidibus' interest in balance is an extension of Zodiark's will, it does kind of raise the question of why Zodiark and Hydaelyn ended up fighting. If it were true, he should have had no problem with a Light-based counterpart to himself. Which would imply that Hydaelyn was the aggressor. I guess we'll find out.