Yes, they were sold at Big 5, Sports Authority and even TW. I can remember Pro Tours going for 59.99 on TW at the end of production. What a deal ! That was around 2000. Probably a better racket than the $200 ones they are selling right now.
It should be noted that Head never changed the published specs of those frames with regard to their composition. I'm sure they continued to put the same nanogram of aramid fiber in each frame. You guys understand marketing, right?
I'm don't think the Radical was ever represented as a twaron frame. Twin tube was the selling feature on those frames. (Although the final version was sold as not having twin tube construction.) The Pro Tour was a twaron frame as were some earlier rackets like the Electra.
I had one of the closeout Radical frames. Good racket but I didn't like oversize so I sold it.
I will say that I have plenty of old great playing frames that don't have any kevlar/twaron etc in them at all. As well, twaron has disappeared from the marketing schemes entirely even though it is still readily available. There is a new gimmick every year in case you haven't noticed. And they are all ground breaking technologies that will take your game to new levels.
See a trend?
Long story short, probably Chinese, don't worry about it, still a great frame, regardless.