Mixing floral powders in minecraft will yield the corresponding vanilla dye object however placing a floral powder into a workbench will not convert into dyes. currently the only workaround is the forge lexicon which is disabled on many servers. Most mods accept the floral powder as a dye however there are some mods that seem to ignore this thus a direct conversion recipe is needed for all associated floral powders to their corresponding dye

The floral powder will work as a dye for any mod that has been correctly implemented, if there is any that are not accepting them then you should talk to that mods dev as they are most likely not using the ore dictionary for the dye in their mod

The possible exploit to this: automated Lapis Lazuli or Bone Meal production.

than those specific recipes can be excluded i was mostly talking about the specific colored powders
i had said convert floral powders to corresponding dyes. lapis is actually a gem and bonemeal is its own thing so they are special cases.

for example red floral and yellow floral will make vanilla orange dye so ergo orange powder should directly make orange dye that kind of stuff

though on a side note i am not sure how usefull your ""Exploit"" would be as bonemeal is not exactly a rare item and one swing with a TK hammer and you get stacks of lapis from single vien so neither one of those is really a Rare or valuable commodity

The potential exploits are more evident if you consider early game and skyblock type packs.