Yours if I am not mistaken is the initial batch of Wira isn't it? 1994? Seems like they directly inherited the glue/adhesive problem found in Mitsubishi cars in that era. When rebadge, follow everything including manufacturing methods.Actually thought mine escape the rust problem. Many within 2 years already pop out. Mine I bought second hand already 4 years old from mechnic's brother. Rust came after 2 years of use meaning total 6 years before the rust pop out.....
Your car is at top tier sleeper level.For mine I totally replaced the whole roof, get rid of the rust once and for all :)