So your definition of filler is "the rotation that has no failure state"?
Respectfully, that's not a definition of "filler". Filler is that thing we all kind of know what is, but don't have a clear definition. What we can do, though, is see if a given definition DOESN'T work. Yours does not. Example:
GNB 1-2-3 can be performed in the wrong order, such as 1-2-2 or 1-3-3. These would be failure states. You can't spam Royal Authority, as that would be a failure state. So your definition means any 1-2-3 combo is not filler. BUT, 1-2-3 combos are considered by everyone to be filler, thus your definition does not hold.
I think a better definition is one used by the Balance guides, which can be worded as "Actions that occur outside of burst/mini-burst" or "Actions without CDs used in a standard rotation". If you rolled your face across your keyboard, which actions remain not on CD once you're done? What is the correct rotation using those remaining buttons? THAT is your filler.
By this definition, GNB's filler would be "GNB's 1-2-3 combo and using Burst Strike to not overcap Powder Gauge". That is GNB's filler. The No Mercy window is obviously not part of the filler. There's some parsing around whether Gnashing Fang and Blasting Zone constitutes filler or not, but at least that's a more useful definition than "no fail state".
Fire 4 is part of filler: https://www.thebalanceffxiv.com/jobs...arget-rotation
The basic BLM filler is Blizard 3, Blizard 4, Paradox, Fire 3, Fire 4, Fire 4, Fire 4, Paradox, Fire 4, Fire 4, Fire 4, Despair, refreshing Thunder 3 as necessary and not overcapping on Xenoglossy.
The basic SMN filler is Summon Titan, Gemnshine, Astral Flow, Gemnshine, Astral Flow, Gemnshine, Astral Flow, Gemnshine, Astral Flow, Summon Garuda, Gemshine, Gemshine, Gemshine, Gemshine, Astral Flow, Summon Ifrit, Gemshine, Gemshine, Astral Flow, Astral Flow, Ruin 3, Ruin 4...or something thereabouts.
RDM's basic filler is variable in reaction to Stone/Fire Ready procs, but in a general sense would be Jolt->Thunder, Jolt->Aero, repeat until burst ready, and substitute Stone/Fire for Jolt as procs allow, and swap Aero and Thunder as mana requires. This is why people consider RDM to be very easy to pick up because the filler is really straightforward (and so is the burst).
Bahamut, Pheonix, Enkindle, Energy Drain, Fester, are all considered cooldowns, and so aren't really a part of filler.
Though we can argue about the extent of filler, "Thing you do when everything is on CD" is probably the general definition that most people subscribe to. "no fail state" is not a possible definition of filler, as it would mean that even basic 1-2-3 combos, which everyone recognizes as filler, aren't filler under that definition.
And you really need to stop saying "aspected ruin 3". There's no such thing presently. It's one of those things people say because it makes their argument sound stronger, but again, "aspected Fire 1" isn't a proper definition for Fire 4, and no one would accept it as one. You can call it "Gemshine", but stop calling it "aspected ruin 3". Unless you're ready to start calling Fire 4 "aspected Fire 1".