The speculation that the upper temp for the stator / insulation is at 100C / 212 F seem way to low to me.
Not saying it is wrong...because I have no hard info
Just thinking ....the engine water temp is regulated at around 190F, most oil temp is regulated around 270F (so the water boils off and does not accumulate). So the normal running ambient temp in the stator housing is certainly above 150F...maybe as high as 200F.... Then there is the stator waste heat to dissipate. Think of a 400W light bulb in that inclosed area...how hot would it get? 300F? higher?. There iss minimal oil cooling it seems... so the only cooling is heat transfer via the aluminum engine cases...and the exhaust pipe are close to help keep them hot.
my guess the stator/armature should be designed to withstand 400F or 500F 195C to 250C.
again these speculations are just trying to use logic to come up with a guess.