Unless you really want to, don't play Touhou games for scoring. Because scoring is very tedious and takes a lot of effort and memorization. It's just a completely different ballpark, and frankly, it's probably more impressive to get through the entire game with minimal bombs or dying.
Trying other teams might be a good experience, but in all honesty probably not worth your effort if you're not interested. You're essentially playing the same game over again, just with a slightly different feel/strategy. Don't do this unless you're interested.
Now that you can clear Hard quite easily, you have a choice. You can try going for Lunatic, or switch to a different game. Lunatic is essentially the same as Hard except for a higher difficulty, so if want to play some new stages and bosses there's really no reason to keep playing IN.
As for which games to switch to, here are my suggestions:
EoSD: Going back in time might be slightly disappointing because of the overall quality, but this game certainly not a piece of cake. Not a bad choice, but you might have some difficulty with it initially, especially without a hitbox.
PCB: This is the "essence" of Touhou, so if you haven't played this I would recommend it. It's very bright and fresh, as opposed to IN's darker atmosphere. Maybe not as hard as PCB for stages 1-3, but 4-6 is debatable, depending on how you play. Good choice here.
MoF: This would be going to the next game, and in my honest opinion, probably your best choice. It's very refreshing compared to IN, and the patterns are very purist, as opposed to IN's synthetic feeling cards. You'll definitely have to input some effort into this, as there is more dodging involved. Highly recommended.
SA: If you enjoy the dark atmosphere feel of IN, SA is the closest you can get. SA pulls a lot of new gimmicks not found in earlier games, which is difficult for beginners, not someone as seasoned as you. It's also relatively tricky, possibly harder than the others, and the spell cards are quite creative in comparison to the rest of the series. Next best choice to MoF.
*StB: I could give a review of StB and tell you if it's a good choice to switch, but in all honesty I think StB should be a supplement to any other Touhou game you would play, as it's nothing but spell cards. It's great for practicing and getting better overall... for the first few levels anyways. The last levels start to get more and more BS, but still a good game nontheless. Recommended in addition to whatever other game you pick.
