These are "low" fingerings. Some print editions use the words "lo" (and "high" when necessary) to identify them and some just use the hyphen before the low numbers. There is no standardized method in braille music to show these. I've experimented with a few different options and the only one I've landed on that doesn't cause some other confusion is to use dots 12 after a "low" finger number and a dot 1 after a "high" finger number (if so marked in print.) The low finger number will look at first like a finger number 2 after the fingering printed, but with a proper TN I think the confusion will be mitigated. (I had hoped that using a sharp or a flat before the fingering would be an easy solution but of course, the combination of a flat and a finger number 2 would be a down bow! Definitely not a solution.)
Hope that helps and if you think of another solution, please share!