Oh,.. god come on bro. I get it you're team IPB. I have been here a long time too. Clearly I support IPB.
I don't understand how the theme cache works, can you help or you don't know either?
To answer your question, I have a site that looks like hell because the cache won't rebuild. I either get [[Template core/front/global/globalTemplate is throwing an error. This theme may be out of date. Run the support tool in the AdminCP to restore the default theme.]]
Or I get no CSS at all. Haven't found a way to fix it.