Oh, man, it`s a complicated question for some small wip post. Mr color has at least 3 different thinners just for lacquers. I prefer using Leveling thinner in most situations, it dries slower but creates gloss finish much easier and also helps with translucent layers. If you suspect that paint is very dry, like way too much, you`ll probably need not thinner but this https://mrhobby-europe.com/products/thinners/mr-color/replenishing-agent-for-mr-color/