Custom games are about as solved as they’re gonna get, the tint variation was removed but people will still kick players with low games. The point of matchmaker being the first tab in play on top of it giving rating for custom games dependent on certain factors makes it the best place for new players to first get acclimated. There is also an advertisement for the Discord on that tab.
The role you’re talking about is also not really a trainer role. You’re talking about some like community ambassador thing, which some trainers do, but it’s like investing 20 hours on a new person who plays 2 games after and then leaves the community after. It’s incredibly draining for a lot of people and has extremely rare payoffs.
When it comes to getting better at the game 80% of it is having the inner drive to actually play it, whether out of fun or competition. It’s why trainers will ask for replays to help put people on the right track since it’s a small time investment that can naturally build up if the person actually is motivated and comes back for more advice.
Regardless new players are going to be told the same stuff every time, it’s another reason the huge time investment on new players is incredibly unappealing because you’re just reciting a script. It’s why most of the guides were written and why some of the faf new player videos exist.
Trainers are also not a retention tool just purely by the scale of FAF. FAF gets what? 300 new registrations a day? We have maybe 3-4 people any given hour of a day around to help out new players? The improvement would be absolutely marginal and contrary to what you said, it would actually be the guides and tutorials that could make the difference there.