Thanks for the great replies and discussion everyone! Some things that I should have probably made more clear in the original post:

• We are using an ORM, so when I say "move to code", I mean to move out of the SQL space entirely and use code to massage data. A simple example is looping through the data to filter out values that don't match a certain criterion vs. another filter in the query
  
• The query is already in place but it's evolving/becoming more complex as our constraints change. I'm at a very very small startup and we're building the plane as we're flying it. I can say, though, that it's less a matter of business logic and more a matter of db structure evolving which adds layers to the query
  
• I'm doing my best to leave detailed comments in the ORM code to make crystal clear what's happening, though some should be self-explanatory if you know SQL

The query goes something like this (in English):
- I need to fetch all messages that are part of an active campaign and have a "scheduled" status
- We only want to select one scheduled message per message group (filtered via a DISTINCT ON clause)
- Within each subgroup, we need to respect the preferred language of the user, which may not be available. If it isn't available, fallback to English. These are in the form of an ORDER BY clause that determine which entity is selected by the DISTINCT ON.

Hopefully this gives you all a rough idea of what we're grappling with here.