As usual, +1 all across the board haha
LHad a long read through and thought over some things too... main thing I'd suggest changing though is Instead of it being Accessory Cube* > Flame Crystals, it should be Accessory > Flame Crystals. Reason being, that way there's genuinely no way to go wrong with it. As long as you have the cube/accessory, it's always possible to exchange it. If it's limited to just the accessory cube being exchangeable, later down the line if this gets implimented, I'd think quite a few may have atleast 1 spare accessory that they're suddenly wishing they never opened.
Other than that, everything seems pretty good haha. Was constantly thinking of a flame mark > flame crystal exchange but was always debating how many marks it should be...1k kinda seems in our favour so I imagine, if this does get implimented, it would probably get increased to 1,250 / 1,500 just so some will still see value in getting the trace tickets instead. Imean, unless you love your RNG which most people dont- I can't really see why people would go for Trace Tickets... At most for the weapon bar; but so many are sticking with Void weps so... idk. Then again, 1k does take quite a while to get... Seems the most logical too since 1k is the stack cap. Better yet, make it 500 and you can choose between a trace ticket and a crystal :^)
Only other thing I figured (Which I imagine is quite obvious to everyone) is we could have all the exchanges and stuff at the obvious Raid NPC haha
= Mark of Crimson Calamity = Mark of Crimson Eye = Mark of Dark Recluse
Considering it only has 2 options currently, adding 2 more shouldn't be too difficult... and what better NPC to hold all the raid related things than the NPC that let's you raid haha.
Regardless though, great suggestion! Think all of us was waiting for atleast one of these things to happen and this suggestion genuinely puts them all together! Hope atleast some of this gets implemented.