Working with long dialogue of several minutes, Premiere Pro will contioniously display this error and eventually crash after closing and opening the text window several times
I assume you are working in PR 2024. But let us know your version. I believe that fixes for part of this problem might have been made in PR 24, but that others will not occur until an update.
"...these are 3 different issues (JSON error, words, length). The words/length related errors should in theory only affect either very large projects or very slow systems, as these are timing related."
The comment about large projects explains one reason the problem does not occur for all users/all the time.
Possible workarounds would depend on specifics of your project.