Format Attributes on FGDB writer

Format attributes are specific to each format, in most cases you will not have to do anything special with them and they may indeed not (seem to) show up in your destination file. But "under water" FME usually does process them.

So short answer: you most likely don't have to map those attributes.

Inspect your destination data, both with the Data Inspector and with ArcGIS and if it looks ok then you don't need to worry about format attributes.

(I know, bit cryptic, sorry about that...)

Format attributes are not attributes in the regular sense, but carriers of metadata about your features. The format attributes are generated by the reader (whether you expose them in your workspace or not) and consumed by the writer, depending on the format.

You can e.g. use format attributes to instruct the writer to create your feature class inside a feature dataset, etc.

If you want to write your format attributes in your output feature class, I'd recommend renaming them to something else, e.g. rename "geodb_feature_dataset" to "DATASET" and then treat it like a regular attribute.