Just reading through, noticed you mentioned leaky front window rubbers on green Twingo, just incase they are indeed made of unobtainium, there is a product that may help that I have used on my 68 Transit ( large, heavy window in rubber, even with perfect rubber the weight after a while would cause leaky rubbers), its called (not a joke but sure there’s been many made) iirc ‘Captain Tolley’s Creaking Crack Cure’, its like a clear liquid that you squirt/syringe under both sides of rubber, it creeps into cracks and sets, any excess can be wiped off with petrol etc. from paint and glass, off of eBay, it was a well used only fix from said Transit forum for leaking screens..