Yes they are actually.
I've downloaded some from Viper and some from that Iranian guy on here (sorry forgot his name), all excellent of's by the way
Some I edited myself, just using kits I downloaded.
So that might be the problem. But is there a way to fix it?
Well, it's a bit hard, but let me explain how it works:
When you import a team, for example, over PES United, and you choose to replace another team, for example, in the English championship, the players in that classic team will still override the players in PES United, but they will be transferred to the team you choose to overwrite. As you need a minimum of 16 players on a team, it will fill PES United with random free agent players and cause a big mess. So, you need to apply the team data over the team it was originally created.
Also, after doing this, if you import another team which uses PES United players, it will overwrite those players again, filling the other team with random players, and cause a big big mess. That is what is probably happening in your game.
Yes, I know this sucks.
Now, the "solution":
Firstly, you need to check what teams does that OF replace in game (you can ask the author if it isn't specified in the website/forum post). For example, you can't have the classic teams that use teams from PEU league if you use the SPL option file, since they use the same players/team as base.
You can do some workaround, but that would take about 10 minutes to each team:
1st - Import a team you want over the original team it replaces.
2nd - Use base copy to copy all the players to the team you want to replace. Also apply the kits/logos/whatever.
3rd - Now you can import other team over that original team.
Example:
Let's say you have 2 teams that replace PES United: Celtic and Barcelona Classic
Import Barcelona Classic over PES United.
Base copy (not transfer!) all Barcelona players over the players of a team in the Serie B and apply kits and other settings.
Now you can import Celtic over PES United.
That would be very time consuming, but it should work.
Another solution (which I prefer) would be to create a second playstation user to use a second edited data set, so for example, in user 1 you can play with all the PES leagues (Premier League, Portuguese League, Ligue 1, etc.) plus SPL (and play the master league without the classic teams, which wouldn't be much realistic) and in user 2 you can have a classic teams OF to play friendlies and custom tournaments... Just be aware that image slots are the same for every user, so, unfortunately, you can't have unlimited teams and leagues.
I use this second solution in my game: In my first user I play with clubs and then I have a second user to play with new National teams (by Speckkopf here on the forum, if you are interested).
I hope it helps.