Hi,
I do not agree with you, this is NOT a bug! A textbox is used for the language setting because PayPal can decide to support a new language at any time! If a dropdown list is used, you will be not able to use the new language code and should wait for a new version of the Store module! Now imagine if no one tell me than a new language is available? You could think than the Store module can't work in your country. The language code is transmited to PayPal in the "lc" field, you have to read your PayPal documentation to know which language is supported in your country. If you do NOT read the PayPal documentation, who should you blame, me, PayPal or yourself? :-) If PayPal is available in Swedish, please ask PayPal support or read the documentation to know which language code you have to use. Moreover, in France and with some other country we have found than sometime the lc field is ignored if you do not set the same language code in your PayPal account, even if the PayPal documentation explain than the lc field is applyed over the corresponding PayPal account setting.
Gilles
EDIT: I have just read now the last available online documentation, at the page 372 concerning the lc field you can read:
The language of the login or sign-up page that subscribers see
when they click the Subscribe button. If unspecified, the
language is determined by a PayPal cookie in the subscriber’s
browser. If there is no PayPal cookie, the default language is U.S.
English.
May be the different behavior between the sandbox mode and the normal mode is related to the PayPal cookie!? You should try to delete all cookies from your browser.