Neat bike! Love the color. Well the whole bike really. You should start a thread just for it. It's sweet!
I have 2 braze on derailleurs in my bin. One is a Sachs/Huret. It has a collar adapter and mounts from the side. The other is a Suntour and mounts through the front like every other braze on front derailleur I've personanly seen (which is not many). Anyways.....It looks like your bike could take the Suntour one. Does that Huret you have on there now have an adapter? Looks like a strange duck to my braze on derailleur noob eyes......

Welcome to bike forums!

Hope you don't mind me posting a pic or 2 of your bike for you.......I love it!
Weird derailleur:


The money shot.........Soooooooo cool! I want! (In a 52cm please)