Twintania in a nutshell

[Yenn]

Pretty sure you're the only guild in the world seeing this Fireball bug (or at least only one with any consistency?), and Summoner burst is fine on Conflag if you position them under the boss for Bane + Fester.

Fireball timer literally happens ~2 seconds before Waxen duration is out, and impacts right as it goes away (Unless you're standing directly under the mob, maybe? I don't know). We have never, ever experienced it "Refreshing" stacks or anything. Perhaps its hitting pets and you are mistaking it for a refresh or something?

I posted it in the bug section and it was accepted. I also linked a video of it (but the FC didn't intend for that video to be public).
With that said, killing 4 stack Conflags with SMN really cuts it close, even when it doesn't bug. Bane + Fester doesn't really provide enough damage and Aetherdam cooldown is so long that one of the Conflags won't have a stack up to use Fester.

We're resorting to the same strategy as you (or maybe not, I don't remember which group is using it), which imo is really stupid and definitely isn't intended.