I'm p sure most people aren't bothered and I know some of 'em would really appreciate some kind of mixing work.
As for patience, you can always upload a demo until they send you a "full mix" although idk, when you're working with amateurs (us) you never know how long it'll take.
just so you're aware, one reason it doesn't feel "mixed well" here is because the vocals are in a different range than the original and competes with the instruments for space in the same frequency range-- like, the low notes of the drums and bass synths interfere with the low notes of the vocals.
Remember, really good arrangements include space for the vocals! If you take the vocals out of their space and move them around, there's no guarantee that they'll still sound good!