[saluki]

I would consider a rewrite, if anything else for security, has the existing code base been updated to run on PHP 7.3?

I would look at using the Laravel framework for the rewrite.

This would also offload maintaining the existing framework, templating and ORM. Plus you'll gain lots of features already in the Laravel framework that the legacy framework probably does not have.

Does the app have modules or components that you could start moving over to Laravel one by one?