It's not likely to be the Pledge re acting with the decals.
I've used it quite a few times with both OEM and aftermarket decals and have not had any silvering problems.
I assume there are some left over decals, or even carrier film from the sheet, give these a go on some scrap plastic, this will let you know if the decals are sub standard.
Failing this, it may be a good idea to locate some aftermarket decals, and strip your old ones off.
I have never heard of a way to repair silvered decals, and so far have never had to try and find out.
Touch wood.
I use Pledge on all my clear parts, and never had one go cloudy.
If it's possible, apply some more Pledge onto your canopy, and it will 'undo' the cloudy section.
Or use some Windex, this dissolves the Pledge, just apply it with a cotton bud.
Don't dismiss the miracle work that Pledge can perform.
Even my dull coats come up a treat after mixing Pledge with flat base.