No idea if this is already know, but there is a bug in the comments extension (latest Sienna version 0.9.11).
When you use the pagination to go to page 2 for example but you have the comments at the bottom of the page, not on top, the anchor link is wrong.
In the comments.functions.php the generated anhor link shows /xxxxxxx#comments#comments which is an invalid anchor and so it simply goes to the top of the page instead of the comments area.I fixed that by doing the following:
I removed the "#comments" from the url creation as its already added by the function above this part.
Removing that fixed my comments issue and when I now click the pagination it automatically shows the area of my page where the comments actually are instead of the top.
PS:
I am not sure how you do prefer to recieve bug reports.
I know you have some system where you keep track of things and where people can post what they found but to be honest..........I dont understand so much how that works