WHO SUMMONS THE ANCIENT ONE
From what you posted in the thread, cyborg angels can be a fun theme! In all honesty I don't engage with that kind of aesthetic a lot though lol so I can't give specific suggestions, but you mentioned being open to general advice so I'll see what I can do.
Ah in all honesty I think I made a few mistakes with the Jelveil traits that I wouldn't repeat for future species. For example, having lots of add-on traits right off the bat-- it made things a hassle to approve/disapprove on both the moderation team and the community, as fun as they can be-- that and just a lot of traits in general. Some people love it, while others find it difficult to work with. I think it's good to strike a balance between how complex you want your traits to be, but this is highly subjective and depends a lot on what you're going for.
Whether traits or lore are more important will also depend on what sort of community you're hoping to grow. If you want to attract people who value aesthetics, you'd want to give 'em fun traits to work with. If you want to attract people who focus on writing and character development, you'd want to give them solid lore. I've seen both types of species be successful, so again this is a matter of what you'd prefer to see in your community.
In terms of lore, though, I encourage you to give more general lore that your community can actually work with when writing their characters. Oftentimes, I see CS lore confined to just the origin story of the species... origin stories aren't bad whatsoever (in fact, the circumstances of one's becoming can affect the person they grow into) BUT if there's nothing else to help your community develop their own characters, then oftentimes it just isn't effective lore. This is especially true if said origin is no longer around and doesn't affect the current living members of the species whatsoever. In other words, consider what's actually relevant for someone who isn't you to write their characters of your species.
(Of course, do write about your species NPCs! Have fun! Just note that this doesn't constitute as lore anyone else can use-- give your community something too!)
Another thing I find important to consider is how accessible or well-organized your species' information is. Personally, I like using TH pages in Worlds to store information, and I'd recommend having everything important all in one place, like a directory to specific pages so people aren't looking for stuff all over the place. ESPECIALLY do not make it required to join a server or a World to gain this information-- how are people going to know if they want to join if they don't even know what your species is about?
(This is also a personal nitpick, but I dislike layout-changing CSS on Worlds. I find it hard to navigate. I'm also not a fan of Discord currency bots-- I know some find it much more convenient, but it locks people who don't have Discord/don't want to join a server out from accessing the currency system-- if you have one!)
All that above and just interact often with your community; it helps!
Of course, this is some fairly generic advice; my apologies. If you've got something more specific (I saw that you did end up posting more specifics in your reply to Aldwyn, but I was still writing this post and I didn't see it, lol), I'd love to give you a hand, though!
Running a species can be very rewarding, but it's also lots of work. Nonetheless, I wish you luck!