Required secondary locale check bug for multilingual input fields in submission steps

Dear PKP staffs and Forum members,

I am currently operating OPS3.3.0.8 (PHP7.4).
On the submission step 3 (metadata input) form, the primary locale (“ja_JP”) is required for input fields such as the title, abstract, and keywords, but the secondary locale (“en_US”) is not required.
ex.) In case of title field

        {fbvFormSection for="title" title="common.title" inline="true" size=$fbvStyles.size.LARGE required=true}
                {fbvElement type="text" multilingual=true name="title" id="title" value=$title readonly=$readOnly maxlength="255" required=true}

As above, “multilingual=true” and “required=true” are specified, but input a value in the title field of the primary locale, skip the title field of the secondary locale, and proceed to the next item (abstract, etc.) When skipping, the mandatory check for the title field in secondary locales is not applied. Also, pressing the [Save and continue] button does not result in an error.
On the other hand, if you click the title input field of the secondary locale or focus the title input field with a tab key, the mandatory check will be applied.

How can I get the required checks for both primary and secondary locales even if I skip target fields for secondary locales?

Best regards,
Minoru Tanabe.