Yes, treating long-covid with vaccine helps some. It's an improvement, but it's not perfect. Some that have permanent damage won't improve. Some got worse.
About half had no change. More studies are needed.

I hope vaccines give some protection against reinfection for the long-covid patients so their condition would not get worse.

More testing means catching the virulent cases early, when treatment protocols can have better outcomes, avoiding long-term Covid problems and reducing the virus's spread.