The SOCH site is now translated into English. Visit www.kulturarvsdata.se and let me know if I messed anything up (its bound to happen eventually). If what you see resembles Swedish when its not supposed to, just refresh your browser to clear the cache.
And yes, the Flea toolbox for application developers is also translated. The detailed description of the SOCH (non-SRU) API will soon be available in English as well.