This guy I swear is looking at my internet search history… The closers most popular around here are the sprung chains in a cylinder hidden in the hinge style. Not sure they have close/latch speed options though. I need to sort out my garage and stairs fire doors, as they are currently always held open by a fire extinguisher (for irony) and a stuffed dog respectively.
How about carving replacement buttons and bezel out of some hardwood? Finished with an epoxy based varnish it should resist the bleach fumes.