Currently the trails use the names as they exist in the code. Which, quite frankly, looks ridiculous. Some examples of bad names: reddust (redstone trail) ColoredRedDust (colored and red, wow. Rainbow Dust would probably be a better name) mobspellambient (ambient potion effect) endersignal (eye of ender) InstantSpell (instant/health damage potion effect) townaura (mycelium particles) wake (fishing trail (the little trail you see when you're about to catch a fish)) etc I believe the names should be more user friendly. Because the current names look confusing to the users.
+1 You don't know what half of them are without looking at pictures atm. This may also help sell the feature to people that think "Wow, it would be cool to have a mycelium particle trail" rather than "Wtf is townaura"
If the command is /trail (i dont even know) then it should be like: /trail redstone /trail potion1 /trail ender /trail potion2 /trail mycelium /trail fishing
Hmm... wouldn't it be cool to save your own custom trails? /trail save /trail load Bit off the main topic but...
Counter Suggestion: Give each of the trails aliases, much like items. Since I have the "Happyvillager" trail I would be able to type /trail happyvillager, /trail greensparkles, /trail green, /trail hv, etc.