If you are using enamel thinner, chances are that it will slowly "eat through" the laquer gloss layer. Its recommended to re-coat the area again after a few tries with enamel thinner. Also, spraying a gloss coat might dull your gold paint if its metallic base.

Metallic paint and gloss coat don't really go well with one another (unless it is a gloss coat for metallic paints). If you apply gloss coat, it will reduce the metallic shimmer as the gloss coat dulls the metallic particles (at least that's how I think it works).

Reverse wash - People normally apply a gloss coat to protect the layer underneath so that when you spray enamel paint on top, the lower layers are not affected due to the protection given by the gloss coat when you clean it with thinner/zippo.

Like General Nic says, use Zippo Fluid instead of enamel thinner. But no matter what, if you keep on using Zippo Fluid or Enamel Thinner over and over again, the thinner will eventually eat through the gloss coat and affect your lower layer of paint.

Gloss coat is a layer of protection. But the continuous use of enamel/zippo fluid willl eat the gloss coat it. Try experimenting on a part - keep using the enamel thinner/zippo on it. You will realise that eventually the gloss coat will come off as well as your paint.

You can try Tamiya Limone cement. it melts plastics and not that overpowering of a smell.

Best not use any lacquer based gloss or clear coat on the metallic finishes as they will lost their shine due to the metallic particles in the paint being diminished. You can try using an acrylic coat like Future but its a bit expensive.

Strong Oven Cleaner should get rid off it i guess....if can't, DOT3 Brake fluid

Well.... have you tried micro masking? Like how they do it for resin kits. You cut itty bitty square pieces of masking tape and then patiently stick em. Most ppl do it for the Sinanju Emblem but patience is a must. Old bottle paints... acrylic...pour acrylic thinner shake and wait and then stir. Your project can be salvaged still...just use some windex to remove the acrylic.

A few things, think you need to give some sanding on the parts. Normal step (IMHO) would be like this:- Sand- prime -wetsand (for glossy effect) - spray black - gloss coat/ compound - wetsand (optional) again -then clear coat .

Clear black is not a top coat but color.

Mix ratio - should be milk consistency

Yes, curing time plays a role. It could be also that industrial cleaner not properly removed.

Yes. Sanding results in tiny spaces that gives the paint something to "bite" on. Since primer is something for paint to "bite" on also, the bond will be stronger. If airbrush, normally leave a day i guess after priming? Shouldn't spray all your paints in one go....its like you said, the paint won't have time to cure.