Certified copies were acceptable before the Level 5 lockdown (even though it is never an official rule), where the passport application is based on FBR and naturalisation.
I am not sure if this is still the case, as they haven't been progressing any passport application for a long time now. Your best bet would be to contact their WebChat agent during business hours. You can find them at https://www.dfa.ie/passports/contact/
The 'WebChat' button will be enabled when their staff come online.