developers of Grog´s Revenge ?

I watched again Grog´s Revenge and there is marked Sierra-On-Line as developer.

But as Sierra-On-Line is American company, I think it cannot be developer of MSX version. (of course I don´t have any real facts, which says it cannot be)

Sierra-On-Line of course made original American version(s).

Hopefully someone can tell something about this someday.