I’m surprised to hear of plastic recorders tuned to A=415. I admit I’ve never really got into German fingering – but the only A=415 recorders I’ve seen have been wooden, abd often more upmarket models in the Early Music Shop.
A couple of my early plastic recorders were slightly out to A=440 – possibly C=256Hz? which was still around in the early ’60’s. This was just far enough off to make playing with other instruments difficult – and is presumably why my Dolmesch Treble has gone missing over the years.
Good to know about such issues.