I like the idea of the elf-ball style deck, but it's pretty hard just to run it off earthcraft and Rishkar (who only works with creatures with counters on). If you wanted that as a theme, would you consider:
If you don't want to add them, you just have a ramp deck, nothing particularly elf-ball-ish.
Rishkar is fine, but he's the only one who works with the other counter cards to make them ramp, which makes him kind of essential for the deck to function, and he's pretty vulnerable.
There isn't much that makes it particularly selesyna, presume you would want some cards which gave you early tokens in white which you're a bit lacking on.
I'm a big fan of mirari's wake, which you have. I find it does a lot to support the GW ramp deck, and draws people into it (just ask Sigh). Ashnods Altar works here as well as you've said, but again is looking for token generators.
Right, onto lands. Lands is a difficult theme. There are so many cards that reference 'lands' there's a tendency just to throw the together and call them a theme. You need to try to think what you're trying to do with the theme in the first place.
It looks like what you're trying to do is move lands between play and graveyard to gain advantage either through the sacrifice of them or triggers when they return to play. Some of the components you've listed are a bit of stretch - tarmogoyf doesn't signal lands, it's just nice if you happen to have one if your graveyard. Criticisms aside, it does seem like a cool theme. You have plenty of ways to get lands back, it's just how you get them into the graveyard in the first place. Discard and self mill is relatively easy and you can pull them from other design strands, but you kind of want to have some more sacrifice stuff, particularly in white to embed it in selesyna if you can.
Solemn recruit is a good start for a swap. Would you want to consider
angelic purge? I know it seems low power but it's good in a lot of different themes. The landfall cards are fine, they're generally good enough by themselves, but better if you're putting a lot of lands into play. I worry Titania is too strong, but might be okay for your environment. Cataclysm would work, but I'm personally not a fan. Also not good synergy in your go-wide elf-ball strategy.
Emeria Shepherd? I'd focus on what white cards can support the strategy otherwise you're gonna have to warp green a lot (which I think would be fine, but you'll change the dynamic quite a lot). I like Emeria Angel here. Is Cenn's Enlistment too underpowered for you?
If you're going to have cards that can search for non-basics, do you want to consider the GW land that puts +1/+1 counters on creatures or makes saprolings? (Mind has gone name blank, sorry).
If you're having trouble with selesyna, you might want to look at your gold cards and what they are supporting/suggesting. Voice of Resurgence doesn't feel it's supporting much, just good stuff?
I think I need to slightly adjust my curve toppers to capitalize on this new trio
