This will most probably affect anybody working with Sobi2, Sobisef and using menu items (every average website has menu to categories).
Not necessarily, since this the cause of this bug is still not clear to me. I was able to reproduce the problem using your test web site, but I did not try all different combination's of category and sobi2 entry configuration. (For example I have another test web site which uses Joomla! Menu Items linked to SOBI2 categories and sub-categories, but it does not have the problem).
It may also be related to your Joomla! version (1.5.15) since the SobiSEF plugin is essential a Joomla! router.php file.
I suspect it is not a Joomla! version issue.
But I agree this is a significant problem and I am surprised that it was not been found previously.
In terms of bug/issue priority I would mark this one as high.
I do not disagree, but there is no mechanism for me to prioritize potential bug reports
what is the usual response time of Sobi 2 team?
Unknown, sometimes Trinity/Neo mark a potential bug report as 'confirmed' in which case it has been accepted as a bug rather than a configuration issue.
Where is the place with bugfix report
Refer SobiSEF plugin RC 1.6/1.7 not creating required sub-sub-category External URL's
where I can see progress, status?
Nowhere that I know of. But I would suggest subscribing to the topic
SobiSEF plugin RC 1.6/1.7 not creating required sub-sub-category External URL's by clicking on the 'Notify' tab so at least you will be alerted of any additional postings to that topic.
Sometimes Trinity/Neo modify the Title of the topic to include "Confirmed" in the Title, other times they just add "SOLVED" and the version number of the SOBI2 Component/Plugin/Module in which a bugfix has been implemented.
Regards - Mark