yeah non-genuine wings are a bit shit. I had a new set and the fit and general quality of them was terrible. Sourced a pair of decent 2nd hand genuine ones and threw the new pattern ones in the bin.
For something like a sill though, you'll have to cut and bend it anyway so I can't see it being much of an issue, not like it's a bolt-on part, once it's the right shape and welded in place you'll not tell.