Using FME version 2019.2.3.1 it appears that if the MITAB writer format is selected within a FeatureWriter that non-standard CRS's default to an arbitrary "LL" CRS based on WGS84.
When tested not using the FeatureWriter this doesn't appear to occur. The FeatureWriter does not allow setting of output Coord. System from an attribute therefore I am required to rely on "Same as source". I do have a MITAB workspace resource but again I cannot set the Coord. System as a Parameter and only as an Attribute in my use case.
Is this a limitation on the FeatureWriter or on the MITAB writer and MapInfo format itself when it comes to very new Projections?