Wagner has has two bits of Latin, but each raises a mildly tricky question of pronunciation:
Qui míhi discípulus.
Kwee MEE-hee diss-KIP-uh-luss. Qui is ‘who’ – relative, not interrogative – mihi is ‘to/for me’, and discipulus is ‘student, pupil’ (same word as English ‘disciple’, but with no religious implications in Latin). Put together, it means ‘(you) who (are) my student’. Commentators note that this is the opening phrase of a Latin poem by William Lyly (grandfather of John Lyly, the playwright) used to teach elementary Latin grammar.
As for pronunciation, this is Renaissance Latin, but follows the Classical rules, where the rhythm is based on long and short syllables, not stressed and unstressed. The rhythm is dactylic (long-short-short), the commonest classical meter, and this phrase is two and a half dactyls: long-short-short-long-short-short-long. If we ignore the word-accents and emphasize the dactylic rhythm, it would sound something like this. Romans probably didn’t do that, any more than English-speakers read every line of Shakespeare duh-DUM-duh-DUM-duh-DUM-duh-DUM-duh-DUM. Then again, Marlowe and his contemporaries probably did read it that way. If we stress the word accents, making the lengths of the syllables secondary, it will sound something like this – not as different as I would have expected. Given Wagner’s pretentious ignorance of Latin, you probably don’t want to recite it too competently.
Quási vestígiis nóstris insístere.
KWAH-see Vest-I-jee-eese NOSS-treese in-SIS-teh-reh. Quasi is ‘as if’ – still used in English compounds – vestigiis is ‘footsteps, footprints’ (related to English ‘vestiges’ and ‘investigate’), nostris is ‘our’, and insistere is an infinitive, ‘to tread on, step on, stand on’ (related to ‘insist’, but with a purely physical meaning). The whole phrase (prose this time) means ‘as if to follow in our footsteps’ – ‘our’ probably means ‘my’ (as often in Latin), and ‘as if’ probably implies ‘if I were making literal footsteps in soft dirt, you should be putting your feet in the actual tracks I make’ – like a good servant. It should sound something like this.
Note: I would not use the restored classical pronunciation, with V sounding like W and G always hard (as in ‘get’ and ‘give’). Two reasons: (a) Marlowe would not have used it, and (b) contemporary audiences are more likely to recognize vestigiis as being related to ‘vestiges’ if it has hard V and soft G like the English word.