I have to write my results in EPSG:4099 and FME does not offer the coordinate system. I found the opportunity offered by safe to define a custom coordinate system by supplying (ESRI Projection) WKT.
The resulting fme file and exception file went into my documents folder into the respective sub-directories of the FME folder.
The webpage explains that by doing so every project in any installed FME version will know the coordinate system. The WKT definition for EPSG:4099 can be found here.
I use the Reprojector to bring my data from EPSG:25832 to EPSG:409, write the results to file, where the writer is set to have a coordinate system of EPSG:4099.
When I import the resulting dwg into QGIS the layer is recognized as EPSG:4095.
When I read the resulting dwg again into FME and check the coordinate system with a CoordinateSystemExtractor then there are no information at all.
Am I producing data in EPSG:4099 or not?



Set the name of your newly defined coordinate system as the output coordinate system tag. This will ensure that the correct Esri WKT is used when writing to DWG/PRJ.