Yes, looks like the old (Dutch) bikes have quite some following in Indonesia. My Fongers Professional (actually a Batavus) classified triggered quite some traffic from Indonesia(!) ...but that was after I has decided to preserve it for my own collection, after a year of advertising. With BF-regulars it didn't evoke much. For them not familiar with Fongers: original Fongers is the Mario Confente of Dutch bikes.
My Fongers Professional meanwhile got a full overhaul using solely original equipment >>>
I am really looking forward to you keeping us up to date on your research project and scans, Italuminum.