The problem with these type of signings (your Tchouameni at Bordeaux example) is are they going to be good enough to play and/or get enough games to develop that Klopp doesn't every to his trusted players over them. We'd need to make it clear that was going to be our recruitment strategy and have Klopp be happy with it otherwise it's just going to end up with a fair few heading out on loan
Normally they won't be trusted but look at the age profile and depth. I don't typically advocate for these types of signings as we have an established winning side, but it's the depth and age profile for midfield that's the issue. They can't be the only signings, but if we bought a senior midfielder and a young one, you'd at least have the energy and depth. That's it.
Not saying we start signing unproven 20-year olds left and right, but there's something to it. A player like Carvalho is of course not ready for consistent first-team football but despite his age and lack of experience, he at least is a squad option and has already contributed when our forward line wasn't available (Nunez red card and Jota injury).
It gives us options, that's all.
If they are advised right top young players would want to play regularly and develop. We just need to continue doing what did the past years successfully but to be honest it's becoming more difficult since we don't have players we can sell for big fees and the English clubs throwing money like crazy.
The cost is the issue. Maybe we've got it lined up next summer, but if we're looking for young, talented, and also proven players, the secret is out. We had the jump on data for players, but it's increasingly difficult to find those types of signings at a good price.
We've clearly tried, but it's certainly not easy.
The best option will be contractual situations, and that's how Real got Camavinga and Bayern got Gravenberch. Porto's financial problems gave us a great deal on Diaz. Maybe Laimer on a free is a start for us.
But if you're trying to sign multiple midfielders to rebuild, it's not easy to sign them at affordable prices, and beat out other teams at the same time. So maybe one of the signings is a younger, more "risky" player.
Just some ideas.