I highly doubt it since Light is probably a really specialized type, with Wizard King / That stupid elf poser being the only ones that we know of that have had the 4 leaf clover book with the light type.
Then...Tabata should just give the king useless "Shining Magic" that just makes him really shiny when he activates it (but is still somehow really impressive cause it's a LOT of magic power lol) and that's why he didn't become a magic knight like other royals.
As for the guess
"Asta is eventually going to get full access to the purified form of his grimoire and will be wielding Licht's sword magic."
For this I both think and want it to be no. Because if Asta's grimoire gets purified then there's neither demon nor 5th clover which is what makes him special (and I always assumed the 5th clover was the titular "black clover" since that's the only thing that made sense to me lol). I think sword-wise, at some point he'll get his second sword back from Licht, keep the 3rd sword he got this arc and just end up with 3 swords with different properties for different scenarios. It'd be interesting to see him use the two smaller/lighter swords together since they both presumably are easier to swing and both do special stuff with magic (one channeling ally magic, the other asborbs/removes enemy spell effects)
"Asta won't get access to mana, will keep his anti-magic ability, and will specialize in his demonic form."
Yes.
Nero is...
a) a bird with Licht's soul inside
b) a bird with the first Wizard King's soul inside
c) a regular bird
So...I think we can rule out "regular bird" from the get go lol. After being shown to detect special swords and magic stones and somehow being drawn to Asta, him being a normal bird seems improbable. I had never thought about him having Licht's soul, rather just being tied to the elves, but that would be interesting and there was weird stuff going on with Licht when he reincarnated.
Noelle will at some point form a contract with the water magic elemental (Undine?)
This one is tricky for me. It seems fair to assume that the spirits go to whoever is meant to be the strongest user of their element and it's fair to assume Noelle would be the strongest water user by the end of the series. Additionally, Noelle straight up has a living entity inside her wand (Bruce...from the light novel...sigh) so maybe that ends up being the spirit. However, out of 4 known kingdoms (and even then, that's just on there continent and not counting the Asia-equivalent Yami's from), Clover already has 2 of the 4 spirits so getting even one more would be stacking it too much when there are two known enemy kingdoms. And when I think of a potential fight between Noelle and another water user with the spirit, I can't help but love the idea (makes me think of how Fairy Tail had fights between "X-Type Dragon Slayer" and "X-type God Slayer" for example).
My official "feel free to shame when wrong" answer is no. But I'm not convinced.
The reincarnation of Licht/Human Princess' unborn son is
a) Asta
b) Yuno
c) Yami
Going with the safe Yuno bet here. Him getting possessed an elf and yet not losing control of his body and having "no sense of self" for the first few minutes of the possession makes to much sense for an unborn baby. Add to that him using wind magic like Tetia and Raia referring to him as "Licht's..." in his mind and I just don't see how it's not him.
The massacre of the elf village was caused by a closed time loop created by Fake!Licht's light magic being sent in time by Julius Novachrono. (having just caught up with the anime, that scene in the anime REALLY supports this theory)
Now this one...I thought was funny to think about back when Julius negated the attack in the manga and you brought up that theory, then the anime episode happened and yeah it legit looks like a time portal opened. I'm looking at it again (it's in Episode 46, at around 17:40 mark for anyone curious...wish I could gif things...) and the circle around the spell looks like what you see on Julius' magic and then the actual light arrows look like they're just flooding/bursting out of a portal. When Patry used the spell to kill the Clover people, there was no circle around the spell itself and if Patry has the same magic as the 1st WK, then you would expect the 1st WK's spell to look similar to Licht's.
Mimosa is the reincarnation of the Human Princess. This would explain why Mimosa was recruited into the Golden Dawn, even if Fake!Licht hates royals, he was still attracted to her soul. (Also this is going to be awkward if Asta or Yuno are the reincarnation of her son)
This is very interesting! I just figured that she looked like Tetia because she's a descendant (not direct descendant since Tetia was killed) and that Patry picked her because she looked like Tetia. However, her being a reincarnation makes a lot of sense because it makes sense that Licht would try to save his wife along with the other elves and we know Patry can tell who's a reincarnation and that would perfectly explain why she's in GD (and feel more real than "you just reminded me of her")
Asta's demon is
a) The demon the original Wizard King sealed
b) another unknown entity
This one I don't even know what to think about lol. The demon 1st WK sealed was Licht and Asta uses Licht's weapons so it seems to track but there is so much going on with Licht's soul that it's hard. Asta's grimoire seems to be a corrupted version of Licht's. Licht had a four leaf clover. Asta has a five and #5 is the "demon"...