u are talking abt using lacquer as base and enamel layer on top, then remove the top enamel layer using thinner rite?
if yes, then zippo lighter fuel should be fine enough to remove the enamel layer, it wont remove the lacquer base layer,
since the fuel is not strong enough to remove lacquer base paint.

nv actually tested b4, but heard they say is not recommended, most of the time they
will apply a clear coat b4 the enamel, and it need to be fully cured only apply enamel paint on top.
coz enamel is stronger, the thinner inside might actually eat through if acrylic not cured enough or
apply too thick enamel. based on wat i understand.

usually painting is after you done all those sanding & glueing, from my own understanding, cement content quite lotta solvent,
which will melt plastic, which it should, in order to bind 2 parts together, so it would definitely melt the weakest acrylic paint, I
think it will melt lacquer also, its just simply its job, to melt.
nothing wrong with pre-thin paint, its ez, no need to fiddle with ratios. actually its not hard also, can look for EA gunpla in youtube, he
got teach thining paint tutorial which i think its quite good.
1 of the pros of the concentrate paint is flexibility, u can adjust the consistency tat u need, even can direct apply using brushes, can't
do tat with pre-thinned paint, too low viscos.