I'm thinking…. when saving, save either svg:x or pdn:x.
When loading, if svg:x fails, split the op at the ':' and then try to load it so that for example krita:glow gets split, ('krita','glow'), ignore the first part and try to load pdn:string[1].
And you could add pdn:glow, pdn:negation & pdn:reflect to Krita's kis_open_raster_stack_load_visitor.cpp?
OpenRaster4Test.zip