With due respect, I would suggest that this coincidence isn't much in the way of evidence. Frog deaths are often overdetermined, so taking a look at the whole situation would at least enable a ranking of the possible factors in the death.
It would have been very valuable to have a necropsy done, and it is a little surprising that someone in your field wouldn't have gotten one done -- such a case would be novel (as far as I can see with the public search tools I have at hand). There are no references to the genus in either Wright and Whittaker or Mader's, which suggests that there are no cases in the herp vet literature. With the near ubiquity of decaying wood and cork in vivs, it seems this should be known if it is a live issue.
I found some references to the genus being a known member of normal amphibian microbiome, and even a suggestion that this is a possible zoonotic pathogen (
here), but nothing that supports the inference in this situation. Do you know of any cases of the genus suspected in amphibian mortality?