I know that - you know that - so why have they not been ordered already ?
Schleicher apparently declined the order for 70+ K21s. I reckon they would do that today, not wanting to devote their entire output to one customer for several years.
Grob no longer build gliders, neither do Centraire, which I think leaves the choices of a PW6 or a Perkoz, both Polish gliders. I have no idea if their builders would be able to fulfil a large order even over a great many years.
The DG1000, Duo Discus, Arcus & Quintus are not basic trainers.