Hi and welcome to AutogeekOnline! :welcome:
Klasse All-in-One is a cleaner/wax or if you want to drill down and get real specific it's a cleaner/sealant. Generally speaking, cleaner/waxes or cleaner/sealants will tend to stain plastic trim as the cleaners will turn white when they dry. The worst trim in the world to stain is the PEBBLE TEXTURED BLACK PLASTIC TRIM and that's because this type of trim has a pebble texture and things like cleaners, compounds, polishes and some waxes will IMPACT into the texture and for the most part be impossible to remove 100%.
That said, I've never noticed the Klasse AIO to be horrible at staining like some products but at the same time a good practice if your car has plastic, rubber or vinyl trim is to do one of two things,
1: SLOW DOWN - Slow down and be careful when applying ANY paint cleaner, compound, polish or cleaner/wax so you don't cream over the trim with the product.
2: Tape Off - If you don't trust yourself to be careful around trim then simply tape it off with some painter's tape.
As for Souveran Paste Wax, one of the benefits to this product is that it doesn't stain trim. It's still not a good practice to apply any wax over trim but if you accidentally get any of the Souveran Wax onto trim just wipe it off immediately and move forward.
