G'day BrowserUk,

Another consideration is context. For example, gnu, the antelope, has a silent 'G' while GNU, the software, has a pronounced 'G'. In this instance, capitalisation might be used to differentiate the two but, I suspect, that could be a rather flakey approach.

There's also a whole a range of TLAs which many pronounce as either letters or words, e.g. SQL/sequel, Tcl/tickle, PDL/piddle. Regardless of whether either, or both, of these forms are correct (for these, or any other, examples), an algorithm to determine whether vowel sounds (and which ones) can be inserted to create a pronouncible TLA is probably not possible.