I think Litematica should be allowed in survival because it helps in building large structures and knowing amounts of resources needed for said building, and generally useful tool. Its client side so no server changes would be needed.
Litematica is not allowed on survival? 
Honestly I think it’d be worth revisiting what we do/don’t allow on survival in terms of mods. I don’t know that I’ve seen significant outrage over any of it but I’ve seen at least a few express concern.