I simply use "anime", which you will also need to add to each of the anime series you want to download. When you are adding names to these sections once you press the space bar, or click away from the field, you will see them change from plain text to little boxes with an X on the right which you can click to remove them.
So in the "Must not contain" section I have add the names of the groups that have releases as Raws only, for example I have and (when you download their torrents they always put their names at the beginning of the filename which makes it easier to filter out) as they were the 3 that I kept getting downloads of but didn't want to. This might be something you add to as you go along, personally I have 1 restriction with 3 different names which just stops the downloading of Raws (anime that has no subtitles). Click the little + icon and this is where you can filter out unwanted things (or add a restriction for only download from certain groups). In Sonarr, on the Indexers page, make sure you are showing Advanced Settings and then on the bottom of the page is the Restrictions section. Now for how I have been handling subtitle only downloads. Categories, I believe, you don't need to adjust, I think Jackett and Sonarr will handle that, but if you have any problems try putting in 5070 which indicates it will have Anime. API Key can be found in the top right corner on Jackett. Use the Add - Torznab option, use any name you like (I always add "- jackett" just to make sure I can see any problems easier), then for the URL, go back to Jackett and click on "Copy Torznab Feed" which will automatically copy the URL, then just paste it into the URL field in Sonarr. Once you have that setup you can add them to Sonarr. Once you have added Nyaa.si click on the little wrench icon to configure it, then using the Category drop down box you can select "Anime - English-translated" which should then only display results that have subtitles, I will also explain another way you can do this below. The following bit of information is something I just realised as I was double checking my Jackett info, so may not be perfect, but thought I would add it as well. I think there are 3 different nyaa options (one of which I think is hentai and uses the category XXX), I am only using nyaa.si as I find it has the better results for what I watch.
Once you install Jackett click on Add Indexer at the top and then search for "nyaa". I would say you should install Jackett which makes it a lot easier to add indexers to Sonarr. I will add my 2 cents, though this is the only setup I use and others probably have some info I don't.