Hello,
The current version of the plugin do not support Sofort but since it is based on "stripe JS", it is possible to improve the support of the "sources" to create a Sofort Source as the documentation explain.
It would require a development in order to let the plugin handle multiples sources, but it's possible.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.