This is probably far more detail than is necessary, but I think answers your questions 😉
Wolsoncroft is a 2nd year scholar (so 17 or 18 years old), was out on loan last week (technically still is until December) in the 7th tier to cover for someone's first choice who was suspended. I suppose the loan is longer than that for either the sake of some rule I am unaware of, or just in case he impresses, which is what happened with Honors loan last season which was extended a few times until it became a full seasons loan
The amount of keepers is at U21 level is owing to unnecessary contract extensions to the likes of Barrett (out on loan) & Kahn (international duty) when we already have Michalski (with the first team), Goddard (injured) & Honor, rather than the amount that we are bringing through. Unsure where Honor is, but he hasn't played since early November so assume he is also injured
They bring through 1 or 2 with each scholarship group as each age group will have their own set of goalkeepers (in 2023 it was Michalski, in 2022 was Honor & Kahn, Will Blease was 2021s offering, Goddard was 2020), which in itself isn't a problem as long as when it comes to offering pro deals, they are a bit more selective
Wolsoncroft and Thompson (who was on the bench last night for the U21s) are 2nd year scholars (and so still qualify as U18s this season), and therefore out of contract at the end of this season unless/until they are offered pro deals
Holt is a first year scholar
imagine Krajewski and/or Garside are the ones they will look bring through as scholars next year to ensure they have 2 or 3 who qualify for U18s in 26/27 season
Edit - Incidentally Kahn is now a full international, made his debut this week, lost 5-0..... at home to Syria