The spell check is active where required. This means:
Terms currently being edited are highlighted. On the Explorer tab, for example, a misspelled model name is only highlighted if the name is currently being edited, that is, the cursor is in the text box.
Language-independent attributes in the Attributes window are not checked, for example, Creator. On the other hand, however, terms from different language columns are checked. This means, e. g., that German terms in the German language column and English terms in the English language column are checked.