I'm having a heck of a time looking up examples, or documentation around saving user notes using SuiteScript 2.x Ideally I'd like to be able to attach the note to a custom record. Any help is very much appreciated.

Why do you need to save the user notes in suitescript, they should save/attach automatically with the native Note UI

Well to give some background on this I have a custom record that in part tracks some customer data from multiple external sources, and when 'source a' says the data should be in NetSuite, but the information can't be found, I'm then using an automated process to make an api call out to 'source b' to try and get the data. However there is the edge case that exists where the data isn't in either of the 'source' systems so I'd like to enter a user note on the custom record to indicate that the information has been searched for, and we shouldn't add that record for subsequent searches.

So you are trying to create a User Note in code that isn't actually a "user" note. It's liek trying to just use the Note mechanism that exists

I guess I hadn't really given too much concern to the fact that this note would not be created by a "user", in this case my "user" is the system, yes. I was planning on using the Note Type 'System Logged Note' which I believe is a default that can be found in Setup > Sales > CRM Lists