I don't have any of the issues in this thread, but I've read it with interest having seen it in Gostev's digest.
The Veeam reps have merged several questions about the folder getting big, and answer keeps being given 'just delete them'.
If that's the case, shouldn't there be an additional option (checkbox?) alongside the retention period to only retain index logs of jobs still on disk, and/or still having the index option enabled for a job - if the job no longer has indexing enabled, and the retention period has expired, the logs should be removed, which it appears isn't happening from the questions on this thread?
Just a suggestion for Veeam to consider.