Wherefore art thou, aberil?

[Mauro]

In all of the numerous examples, there is great variety in what comes after "br", but I have not seen a single case where there is anything between the "b" and the "r", so that certainly makes occitan more doubtful.

Some languages and scripts do not have consonant clusters like "br", and their speakers will insert vowels into them.  Japanese native speakers, for example, would transcribe and pronounce "abril" as "a-bi-ri-ru" or "a-bu-ri-ru".

In Northeast Brazil, a railroad tie is called "chulipa" ("shoo-LEE-pa").  That is what the local workers heard when the British engineers who built the first railroads in the 1800s said "sleeper".  The "sl" cluster is very rare in Portuguese, and never word-initial.

BTW, "April" is written "abril" in modern Portuguese and Spanish too.

I guess many examples could be found. Not directly related to 'br', but for instance Eastern Lombard (You are not allowed to view links. Register or Login to view.) does not like the sequence 'dr' and often (but not always) adds an intervening 'e': 'màder' (mother, cfr. Italian 'madre'), 'pàder' (father, cfr. Italian 'padre'), 'làder' (thief, cfr. Italian 'ladro') (*). In Dutch the sequence 'rkt' is often pronounced with an added schwa, ie. 'markt' (market) is pronounced [ˈ'mɑ.rəkt].

(*) 'làder' is from Latin 'latro', so an 'e' has surely been added here. 'màder' and 'pàder' could have retained the original form of Latin nominatives mater and pater, but I guess they instead were taken from the accusatives matrem and patrem (as happened for most nouns) and the 'e' was added here too for phonetic reasons.