Ask someone you know well from Argentina to buy the ticket for you, bring USD with you and reimburse them with cash. Everybody wins.
Unfortunately Argentinean monetary regulation (if it's possible to name it so) calls for such manual transactions.
All transportation operators in the Sapica network also accept Kitaca, as well as the nine other major cards (Suica et al.). Basically, it's everything except JR Hokkaido, so it includes the city-operated subway and tram, as well as city buses (note, JR Hokkaido and JR Hokkaido Bus are different companies).
That's all. In particular
Ask the booking site to forward a mail for you, translated into the language the site uses to communicate with the hotel.
It might be best to find someone to translate for you. If that fails write in English and add a computer translation in the local language for the hotel.
Keep the message short and ask for a reply.
All places that sell SL Access Cards accept credit/debit cards. Almost all accept cash.
You can't buy tickets on busses or on trains. SL has a help page about buying tickets.
You can use Mobile Phone Tickets everywhere in Stockholm. Just download the official SL app for your phone. It accepts credit/debit cards and some Swedish payment methods.
Ways of ...
Yes, I bought an SL Access card+travelcard from a manned metro gate with a credit card in February 2019. In May 2018 I bought one with value from the SL Center with a credit card.
There is also plenty of retailers that sells SL Access cards and offer topups, probably all of them accept credit cards, at least Pressbyrån does. Check the map here: https://sl....
Since your card is French, it will not incur these fees.
Merchants in Denmark often apply fees (or up to several percent of the sticker price) to payments with cards issued outside the EU, but they are forbidden from doing this for consumer cards covered by the Payment Services Directive II. These rules do not distinguish between Danish and other EU cards.
For what it's worth, American Express in Switzerland includes a Priority Pass in their Platinum card. The annual fee is 850 CHF per year, but there's an offer of 50% off for the first year that makes it 425 CHF, which is slightly less than buying a Priority Pass directly (399 EUR, which is ~435 CHF as of writing this post).
Might be worth getting this card ...