I don't think manually changing their tactics will make a difference. They all have different default tactics in the first place. I think the CPU teams are programmed to play a certain way, despite what the tactics suggest. Custom tactics only affect human players, from what I can tell.
That's a shame, that would have made it so much better. If only we could merge the best things about FIFA and PES we could have an amazing game.
I currently own PES 2017 but I like the FIFA 17 demo. Do you think it's worth getting?