OK. The full story here is that i got a 12mm stud conversion. I'm having a hard time finding 12mm lug nuts with the stock r13 ball seat for the stock wheels. I am currently using washers from urotuning (part no. 70905 ) to get the 60 degree cone seat lug nuts to work with my stock wheels that use ball seats. it's a hassle trying to get the washers to seat correctly and i have to retorque 3-4 times before they stay tight.
The other question that i have is regarding the new wheels that i got which are meant for a Honda. the bolt pattern is 114.3 instead of 112. I already have hubcentric rings. and i know i will need wobble nuts. the question is regarding the type of seat for the lug nuts. From my research, Honda uses an r12 ball seat. which means i would have to get another set of adapter washers, which i will do if i have to. BUT these wheels have seats that are clearly a steel insert that is pressed in. if the inserts are pretty standard then i can buy new inserts somewhere and convert these wheels to a cone seat and avoid having to use washers to work with the ball seat. is there a supplier where i can buy new inserts with conical seats?
That is a real mess you've created.
I would never recommend a 12mm stud conversion. You've just lost strength on the part of your vehicle that holds the wheels on. Just because they exist doesn't mean it's a good idea, and I'd bet that company would tell you there is no warranty and the parts are intended for show use only.
I can't think of a reason an R13 ball seat 12mm x 1.50 thread lug nut would exist, since even 12mm x 1.50 thread size Mercedes lug bolts are all R12. Any 12mm Honda lug nut is an R12 ball seat, and the 14mm thread lugs are R14. R13 is pretty unique to VW/Audi.
For your wheel questions, best I can do is recommend a wheel refinisher to see what they can do for you. I don't know anything about modern alloy wheels having steel inserts (that doesn't seem to make sense, that hasn't been done in a long time) or replacing/installing those inserts. They may even be able to redrill the bolt pattern at the same time.
You must really want to install those Honda wheels on your VW, because you're going to have a ton of effort invested to make this work semi-safely.