The event is probably CHAT_MSG_TRADESKILLS but since Wowpedia's page isn't documented, I have to guess. You can use the command /eventtrace(use it again to turn off) before crafting your items and see what events are firing.
You can use Eventful to see what the arguments passed to CMT are. I don't know if Eventful will work with Legion, but you can try.
Awesome, that is exactly the information I was looking for, thank you very much! I must have searched for craft, create, item, make, profession a hundred times, I don't know why I didn't think of tradeskill.
But I think you could still try the same approach I took and try to use a temporary table to link these events! It might not be the best solution, but it works quite well in most situations and might even be enough in your case. Especially the second code part in my thread describes how to make sure, both events fire within a certain timeframe, just as you have asked for.
Btw.: I refined this approach for my AddOn and added even a third event to really make sure everything works as intended. It still has one small downside regarding AoE damage, but that's just for very rare occasions and therefore is acceptable for now. I just finished it yesterday and had some good testing. Will upload the new version 1.3 today evening if another test works well ... then you can download it from curse and look through the whole code and copy what you need. Maybe that helps as well! ;)
When you create flasks, using /eventtrace, please reply with all the events that are firing, even the ones you don't think are related. My crafting toons are not high enough level for Legion, and I'm not about to make low level flasks, especially since I'd probably have to buy herbs.
I am asking for all the events, because I see BAG_UPDATE on Wowpedia, along with some INVENTORY ones. Might be a lot easier to answer your question if I knew which events fired, and thus what information can be gleaned.