I suppose it's a FW issue, some different implementation of the dictionary stuff. If I remember correctly CR3 uses the same functions regardless of the FW.
EDIT:
If you'll look into cr3pocketbook.cpp in the following method you'll see there's no FW condition.
PHP Code:
void CRPbDictionaryView::translate(const lString16 &w)
Translations are done by calling a system function:
PHP Code:
_translateResult = LookupWord((char *)what.c_str(), &word, &translation);
So there must be some behavior change in that.