That's a bummer on the fenders.
One misstep while mounting or dismounting the trike and they'd probably crack some more.
It may be time to retire them but it's not a total loss. They can be used for the material to weld up other plastics. They would also make a nice wall hanger if fixed up good enough to look alright at ten feet, painted, then applying some vintage style aftermarket decals. Even better if packaged with the front fender and a blown out (unusable) stock tank. That could be hung vertically with the front fender up top, the tank and fenders below.
For full effect, tangled with a nice fish story about how they came off a national race winning trike from back in the day and they're too valuable to put a price on. I know what I got, no low balling!