i think you really shoukd cstch up with the manga before you continue, that way you're less likely to accidentally contradict anything from jjk

Are you planning on giving Shioru cursed energy or just making him use his swords?

I don't quite know anything about JJK (except my interactions with the fandom on Twitter). Regardless I felt like I should at least give you a review and tell you that you're surprisingly well written for your first fanfic.

But you probably learned that through reading others. So props.

what if shirou is the one who kills sukuna? after all sukuna did look like emiya lol but also muramasa in legend he's sword can cut through karma

What an interesting and new way for Shirou to be sent to another world. Although… is Shirou going to have a True Magic under his belt now that he has seen the Root? If I remember correctly, that’s how one gains access to a true magic.

Hope you continute this for a long time.

Anyway, cause a user has open the dam, i gona give my thought about Shirou UBW CT:

Con:
1. UBW the RM has too long of a cast time compare to other DM (a long chant). Maybe he can improve further with a Vow or something.
2. Without Rin, UBW the RM cost too much mana for Shirou to handel. He can deploy it later after improve his mana/CE pool or /and control though (as we has seen with Gojo, he can reduce the cost with good control of CE).
3. Now about the copy weapon abilities, NP usually cost quite a bit of mana/CE so he also need to work on that rather than spam those which is fine for the story. There also a problem of other weapon is not that impressive with some exception (that has been destroy anyway like the Inverse Spear) but Shirou should have some strong weapon from the clash with Gil and Archer, he still need training to learn more about the skill though.
4/ No must hit abilities that normal Domain has but this is both pro and con.
Pro:
1. His RM can not be effect from outside unlike most of other Domain. He can exchange this through for other benefit though.
2. He is actually pretty durable if you remember that though healing he created a sort of amour that can protect himself from Rider direct hit (another way of training maybe) and he got beaten a lot by Archer in UBW. Not to mention active defense like Rho Aias.
3. Maybe he can copy some useful Curse weapon.
4. No must hit abilities so Simple Domain can do jack against him and he can rain a large amount of NP/ Curse weapon so that is not a lost unless he fought someone like Gojo. It should still be able to contest most of other Domain though,

... so I'm guessing we're converting all known magic circuits to Cursed energy right? Because the way I see it only Cursed users can see cursed spirits. Also it works well to how negative of a person Shirou can be.

Survivors guilt having the following: 'irratation, anger, fear, as well as suicidal tendencies.' All that from being the survivor of Angras' flames and witnessing god how many terrible things in the park, then I can confidently place at bare minimum Grade 2 and at most Semi Grade 1.

Cursed technique... well, I guess it can be his Unlimited Blade Works? But isn't that... too overpowered? Look the only reason why he is weak is because 1) he crippled himself daily to activate his magecraft. 2) he had noone to teach how do it.

Put him in a situation where having cursed energy is a boon to Shirou whilst having Teachers such as Utahime, Gojo, Nanami, Shoko and Meimei then he most certainly bloom.

Up to the current arcs, Culling Games, I say go ahead with fully utilising his Reality Marble because there are some ridiculous techniques that can easily kill Shirou without much effort.

Another thing, Shirou is always a glass cannon. He can dish out a lot of damage with certain Noble Phantasm while having the durability of a normal human being. Add him with cursed energy and reverse cursed energy then the problem solves itself.

Yuuta Okostu, a Special Grade sorceror, has the durability of a town, whilst having the most abundant cursed energy out of JJK.

Great chapter. Its rare to see a jujutsu kaisen and fate crossover fic!

Cool concept hopefully you continue it

Write in past tense. Present tense reads really badly

El fic aún esta muy tierno así que veré que resulta de esto o si muere en el olvido.

it's a good idea

just don't don't abandon this like other

anyway keep up the good work

Well Domain Expansion and Reality Marble are pretty similar.