I ran into the same warning messages, when I upgraded Joomla to 3.7.0.
I think if you purchase JoomSEF, then you get access to the paid users forum. Also, ARTIO seems to have a support ticket system for paid users. But paying may not help you at this time, since mitk said "unfortunately JoomSEF is not compatible with Joomla 3.7 yet."
nethead wrote:
joomsef only indexes maybe 10% of the URLs of my site.
I find that sometimes I have to manually go to a page before JoomSEF will index it. So, web crawlers which generate sitemaps are useful for this. Xenu Link Sleuth is one that I use. It is free and you can download from Cnet.com