Ve'nari is farmed in normal maw not the campaign one.
1st get summoned to the maw either by warlock or use raid summoning stone.
2nd get yourself under this bridge -
https://imgur.com/a/hNUf4kj - when you cross it go under it and there will be a small area where you can enter The Maw and the other zone that will fear you every 40s. You want to stand in the Maw zone and ocasionally enter the fear zone and log out so you trigger the event when you log back in that is happening there when
Gorged Shadehound is spawned. Now I think there is another event but I dont know the name of it.
You have to be grouped up with high lvl so you get the rep and if you have really good friend or second account with high lvl that did some quests in the Maw the fear zone should be without that fear and you can just farm that event over and over.
It should give 525 rep per event and it spawns every like 15 min. or so.
I hope I didnt fucked something up here, a video would describe it better then me with broken english but I hope it helps.
I would also like more info regarding Ve'nari rep farming. Can f2p even interact with her?
Nothing interesting for f2p or low lvl players in general there it is just another rep you can get and you also get an achievement for it if you care about that stuff.
Dragonflight reps
Right now there are about 5? reputations that are 100% farmable by vets but I dont exactly know how it works for f2p
And ofc none of this was discovered by me I am too dumb for this kind of stuff, credit goes to ppl on WoW20 discord etc. Thanks.