I've taken the last several days to really look closely at Komento and JComments to better understand their differences. I'm very familiar with JComments as it solved a very tricky problem I had with a complex custom component, so I needed to compare and contrast.
Short explanation: Komento as it is currently structured may not be able to help with that you want (at least not easily).
Here are the details:
To keep this as brief as I can, JComments (even though out of the box it is not aesthetically very pleasing), is actually the richer component. JComments has both object_id and objects_group table columns. You can leverage this to allow you to comment on categories as well as photos. Example: Store a photo id belonging to objets_group "joomgallery_photos" and category ids as "joomgallery_categories".
Komento however only has the cid column. There isn't a counterpart to "objects_group". So there is no way to distinguish ids (at least that I can find).
To give you a more concrete example, let's look at the following breadcrumb from your site (translated to English):
Home » Travel » Iceland »The Golden Circle
The Golden Circle is the category for which you want to have a comment form (for example)
You could do this with Komento, but because Komento effectively is really set up for only one comment type, if you were to use Komento for category comments, you could ONLY use it for category comments. That could be problematic in terms of future-proofing your site (i.e., Komento MAY come out with more features later).
Assuming you will use Komento (and I can't blame you, it is a great extension

), then your choices could include the following:
- Use Komento for commenting on categories only and make the needed adjustments to the related Joomgallery plugin. This is perhaps the easier solution, but note the concerns listed above.
- Use Komento to comment on the individual photos by developing a method to allow the comment form to display within the actual modal window. This option would require some custom coding and probably involve Ajax. Also, no two sliders behave alike, so trying to make your solution agnostic would add another layer of complexity.
IT ALL BOILS DOWN TO THIS: What do you want to do? And how badly do you want to do it? Keep in mind that web sites are for the long haul, and will change over time, so there are serious pluses and minuses that you would need to consider.
I do find this interesting, so I may play with an alternative Komento plugin that is strictly for commenting on categories as opposed to items.