I’m not sure this is a question for much philosophical musing. There is a tradition of Irish flute playing, a fully-formed style; it’s not something we have to conjure from thin air, regardless of how geographically remote we might be from the epicenter of the music.
Rather than trying to develop one’s own eclectic approach to interpreting the tunes, it’s always better to listen to established players who already “speak the language”. If tonguing (or vibrato, or whatever) is the matter at hand, cue up a recording of Matt Molloy, Kevin Crawford, or whoever stands as your own personal avatar of Irish flute playing. Listen…is there much tonguing? It should be obvious, present or not. Some players or regional styles might employ it to a greater or lesser degree.
My own take regarding tonguing is that it really isn’t the right thing to do for most trad playing. In particular, I believe that beginners should avoid it altogether, especially those coming from either a whistle or a silver flute background. Tonguing is a crutch many beginners lean on to avoid learning to play a conical-bore flute properly, with the sort of flexible embouchure required to get the best tone up and down the instrument. I’m speaking more specifically of making intervallic jumps cleanly with no break, and I think you know what I’m talking about!
Tunes that jump between octaves, which may well be most Irish tunes, present a particular problem to the player who hasn’t got their blow right, and the easiest thing to do is tongue the high note. This runs counter to the sweet, flowing style that most of us would identify as typical Irish playing (in the Republic, anyway…), and it en’t how Matt does it.
How Matt does do it, thankfully, is a matter of record, or records. I really think the thing to do is to listen carefully to what the best trad players do, and emulate that. Once you’re an accomplished player in the style, you can make informed choices about what to put in, what to leave out, what needs emphasis, and what ought to be concealed. In the meantime, no sense trying to re-invent the wheel from component parts.
Rob