I think [name_f]Lilliana[/name_f] and [name_f]Lilah[/name_f] are much too close and agree that [name_f]Lilah[/name_f] is also too close to [name_m]Elijah[/name_m].
As a twin myself, I can tell you that being a twin especially a same-sex twin, is very intense at times. You’re constantly compared as if it’s a zero sum game between you - eg “who is the sporty one?”, “who is prettier?”, “who’s more XYZ?”. It’s great in so many ways but it’s also A LOT. So also having matchy-matchy names is too much in my option. Cute when they’re under 5 but not fun for twins - who also want to choose when they are treated as “the twins” and when they want to be their own people.
So my thoughts are that I would either go for all E names - doesn’t matter if not “ah” endings or if you’re going to go for two L names, make sure they’re not too matchy - eg [name_f]Lilah[/name_f] and Loretta; [name_f]Lilliana[/name_f] & Loretta; [name_f]Lydia[/name_f] and [name_f]Loretta[/name_f] would all be good - but not two “Lil” or “Li” names (so not [name_f]Lydia[/name_f] & Lilah/Lyla and not [name_f]Lilah[/name_f] & [name_f]Lilliana[/name_f]. I also see [name_f]Lilliana[/name_f] and [name_f]Lyla[/name_f] as too close somehow).
I would normally say go for different starting letters - ie an L name mixed with [name_f]Delilah[/name_f], [name_f]Aria[/name_f] or [name_f]Sophia[/name_f] but in this case because you already have three kids with all E’s, I think it makes sense that the twins either also have E names or they match themselves - but please make them very distinct.
So, if not all E names, for me it would be:
[name_f]Lilah[/name_f] & [name_f]Loretta[/name_f]
[name_f]Lilliana[/name_f] & [name_f]Loretta[/name_f]
[name_f]Lydia[/name_f] & [name_f]Loretta[/name_f]
[name_f]Sophia[/name_f] & [name_f]Stella[/name_f]
[name_f]Sophia[/name_f] & [name_f]Sybella[/name_f]
[name_f]Sophia[/name_f] & [name_f]Sienna[/name_f]
[name_f]Delilah[/name_f] & [name_f]Diana[/name_f]
Good luck!