While a friendly match doesn't guarantee anything, it's crucial for Manchester United to build their mentality for next season.
Overall, there aren't many changes to the Manchester United squad for next season, so I don't think their performance will be much different unless Amorim can maintain consistency.
Menatally Man Utd this year will be better than last, but they didnt sign any significant player yet, so I think that they will be better positioned but not anywhere near the Europa postion. My best guess is maybe 10th but maybe that is also too much for them. They are now in trouble because they are slowly droping out of the saw call "Big Six".
You're right, I don't think Mbeumo and Cunho are significant players, they might be proven to do well in the Premier League but not top class players, maybe if Manchester United manage to sign Sesko and Emi Martinez then it would boost their performance and enable them finish in a better position than last season.
From their performance in the friendlies it sense several Manchester United players are beginning to improve, Urgate was marking properly, he and Kobie would make a good pair ahead of the season, Amorim should take note of that and stop playing Bruno Fernandes in a deeper position.