Invoice Module - Email / Email PDF doesn't load email from Accounts module

I am currently having some issues with Email/Email PDF function from invoice.

If I link both Contact and the Account with the invoice, then email address is pulled correctly (from Contacts) . However we are using only Accounts and it seems that there is no way to choose where email address should be pulled from although it can be searched manually via the shield button.

Is there ANY way (even modifying backend files and forcing this hard way) to have contact pulled from Accounts? Id really like to avoid creating contacts just for this purpose, mostly because Accounts contain a lot of custom fields and everything we need is stored there.
I tried to look for responsible function but wasnt really successful (mostly because I speak mainly bash and Python :frowning: )

Attached you may find images for better clarification.
1,2 is the when invoice is linked to Account.
3 is the only, manual way, to add email address from Accounts module.
4,5 is the expected behaviour, however it requires Contact for each client.

Thanks a lot!