Ack! what mess!.
Congrats on getting out the wax. That can be tricky sometimes. There are a number of products available in paint stores here in the states that will soften up hardened paint, Sav-a-Brush is a brand name here,to restore improperly cleaned brushes and the like. I beleive most of them would be usable on
curtains it's just a matter of mixing it in a large enough container so that you can soak the entire area. I assume these are blacks, probably
velour? If they are commando cloth or
Duvetyne, then you need to be careful as those products are typically not as color stable as Velour, or real Honest to goodness, velvet. There are commercial dry cleaners that specialize in cleaning large bulky items such as draperies,
etc. These can get real expensive, real quick however. I would only use them as a last resort or if there is a stain , paint or something else you simply can't get out yourself.
There are directions on the Sav-a-brush packaging that detail how to use it on fabrics. 'Course all the usual disclaimers apply, test in an inconspicuous area first , we aren't responsible for anything yadda yadda yadda.