You cannot send dictionaries via personal document service, they won't survive as dictionaries. You have to side load via USB cable, or download with browser.
Dictionaries have two language settings: one that defines the 'from' language, and another for the 'to' language. So to go from Swedish to English, one should be Swedish and the other English.
I'm not sure calibre is the correct tool to use for editing dictionary language metadata. I tried with one of my dictionaries and it doesn't show both language entries. I would use this tool instead:
https://www.mobileread.com/forums/sho....php?p=1927698
With the metadata fixed, and with the latest firmware update for Kindle Touch, if you go to Settings , Device Options, Language and Dictionaries, Dictionaries, it should show an entry for Swedish with the name of the dictionary below that. If you had other Swedish dictionaries you would be able to select one of them as 'default'.
The reason the metadata is not correct is that it didn't need to be prior to the K4 (basic Kindle) and Kindle Touch. Those kindles didn't pay attention to language, and you had to switch the global default dictionary to match what you were reading. The publisher really should update the dictionary to correct this, and you might contact Amazon to let them know of the issue. But fortunately you can change the metadata yourself pretty easily.
Kindle Touch should support Swedish fine in terms of rendering text and dictionary lookup. It should be okay for keyboard entry of Swedish characters as well, though there won't be any Swedish keyboard layout as such. But you can hold down the base character and choose the appropriate diacritic variant. I think it ignores diacritics for text search, in any case. There probably won't be any Kindle Touch updates to add Swedish as a UI language, but that's probably not an issue for you.