SQLITE Reader and FeatureMerger - User Attributes behavior

Certainly the doc seems to echo your thinking: https://docs.safe.com/fme/html/FME-Form-Documentation/FME-ReadersWriters/aboutFeatures/feat_type_reader_usrAttr.htm

In my experience the behavior of this feature is very much format dependent. For example a database format typically works this was as expected - just reads what is checked - but for other formats I've noticed they are just not exposed (as you've seen). 

Not that this is helpful, but I personally almost never use this feature and choose to modify the attributes myself in the workflow with Managers/Keepers - and a big part of that decision I think is the inconsistently between formats.

Hard to say if this is a bug or by design though. My guess is that it's half way between.

Perhaps @nampreetatsafe or @markatsafe is able to comment?

I think it’s acceptable that data formats have different capabilities in terms of attribute behavior when they got read by FME. However I would expect to see the user attribute check boxes disabled for formats where check/un-check can not be supported for technical reasons.