What paint works for "mock" stained glass?
A very simple approach are Window Colour types of paint (example). 

They basically produce removable decals. You can either work directly on the glass or - if bottle design and pattern permit - work comfortably on a flat surface, then transfer it to the bottle. (Or combine both and connect pre-made parts on the bottle with fresh paint.) 

Lines / contours are done with opaque paints, they come in "lead grey" explicitly to mimick the lead of stained glass.

It needs no curing, but is admittedly less sturdy than classic glass paint. Otoh, I've had one design on a big jar for two decades now, including the occasional hand-washing. It has so solidified over the years that it is no longer removable.