Any geologist, especially sedimentologists know that volcaniclastics and indeed pyroclastics are a form of sedimentary rock (once diagenesis has taken place).
Volcanologists might disagree. Welcome to the vagaries of geological terminology.
Granted they are produced by igneous processes initially (from the volcano), but the way they are deposited is akin to sedimentary deposition.
The problem is that this is a gray area between purely sedimentary and volcanic environments. Somehow, I fail to visualize fiamme as sedimentary structures.
A big clue to this is the inclusion of "clast" in the name. Clasts are only found in sedimentary rocks (and deposits), I would be worried if a geologist referred to crystals formed in igneous or metamorphic rocks as clasts!
Sort of like in 'cataclastic rocks'? There is a lot of confusion in the literature here. A clast is a broken rock fragment, regardless of origin and yet a clastic rock is universally recognized as being equivalent to a sedimentary rock. Geologists seem to work around this okay, but just never have gotten around to agreeing on how to resolve it. This disagreement remains despite the fact that YECs claim geologists can are party a world-wide conspiracy to hide radiometric dates, etc.
Likewise if sediment particals (the actual "grains"- not the cement or recrystalised variety) were referred to as crsytals.
How about 'crystal tuffs'? Sorry, GJ, I'm just taking a little advantage of you here. I am glad that you are studying geology and understand as much as you do. Believe me, new worlds await you.