35% for 2 weeks??
damn dude... that is complete overkill! especially for coloured plastics.
usually you take it out periodically, let it fully dry, have a look at it and then put it back if it needs more time.

are your white parts super bright now?

just out of curiosity but was the surface of the jar clean (i.e no sticky label residue to cast a shadow?) or was the surface of the plastic part clean?

with the damaged grey part, the pictures dont look that bad to me, however without a proper comparison with some 'before' pics and a non yellowed FM pics, then i cant really tell for sure.

does soaking the part in water permanently return the colour (i.e. still is a vibrant grey colour after it has been fully dried again over a few days) or is it only a temporary thing??

But, if you are really bothered by it then one suggestion (which i have not tried yet) would be continue to bleach it until it is as light as possible then try to dye that part or paint over it. But just make sure to test with scrap pieces first until you get method right. As some people have found that they melted the plastic from being overzealous.