The current value of the wikibase-propertyedittool-counter-entrieslabel message is "{{PLURAL:$1|entry|entries}}".

The actual number is inserted using other messages: wikibase-ui-pendingquantitycounter-nonpending and wikibase-ui-pendingquantitycounter-pending.

In some languages the number affects not just the form of the subject ("entry" or "entries"), but also the place of the number in the expression. For example, in Hebrew "one" comes after the word, but other number come before it.

By itself this could be fixed by translating ibase-ui-pendingquantitycounter-nonpending and wikibase-ui-pendingquantitycounter-pending to Hebrew, but these messages can have not only entries (wikibase-propertyedittool-counter-entrieslabel), but also references (wikibase-statementview-referencesheading-pendingcountersubject), and the grammar of numbers used for the words entries and references is different.

The best solution would be to let MediaWiki handle the grammar and the number using the messages wikibase-propertyedittool-counter-entrieslabel and wikibase-statementview-referencesheading-pendingcountersubject, rather than doing it in functions in the Wikibase extension (the one I found is wb.utilities.ui.buildPendingCounter(), and it gets complicated further).