If I have a passage of lyrics selected and hit R, the repeated lyrics overlap with the current selection. (The first syllable of the repeat collides with the last syllable of the original selection.) This makes it almost always pointless to use R with lyrics – and it is a disanalogy with how R works on notes.
At some future point, could this be fixed so that the first syllable of the repeated lyrics is assigned to the next available note – or, perhaps, the next available rhythmic position after the full duration of the last note?
(Sibelius had exactly the same issue.)