This may turn out to be a bit of an inconvenience.
I use "" \translate a lot to position text precisely on a score,
because AFAIK it is the only way to do it, as \translate will not work
without something in front of it.
I can confirm that convert-ly does not change "" to " ", as I noticed
the original problem when converting a score from 2.4.3.
Whilst it would not be difficult for me to change all the instances of
' "" \translate' to ' " " translate', I suspect that the positioning
of the text will not be the same, as " " has a length. If this is the
case then I will have to go through all my existing scores and check
the positions manually.
It would be nice if \translate would work with nothing in front of it.