This is exactly how I would number them also and since this is how unRAID numbers them everyone should number them this way to avoid confusion. Sorry, I was just confused by the mention of disk7, which as you say, doesn't exist.
I see this in your syslog
Apr 6 03:09:03 Tower root: Fix Common Problems: Warning: Share S is set for both included (disk2,disk3,disk4,disk5,disk6) and excluded (disk7,disk8) disks
but as you say, that share doesn't have any excludes currently in your diagnostics.
shareInclude="disk2,disk3,disk4,disk5,disk6"
shareExclude=""
Did you change that share's settings after the timestamp for that warning in your syslog? If you go to Fix Common Problems and have it scan again, does it still give that warning?