Is there a way to create custom preferences in Tibco Spotfire?

It is possible to create custom preferences in Spotfire and make them available in Administration Manager. This can be done using Spotfire Analyst API class CustomPreference:

https://docs.tibco.com/pub/doc_remote/sfire_dev/area/doc/api/TIB_sfire-analyst_api/html/T_Spotfire_Dxp_Application_Extension_CustomPreference.htm

There is an example in Spotfire SDK (Tibco Spotfire Developer) called SpotfireDeveloper.PreferenceObjectsExampl. 

References:

Tibco Spotfire Analyst API reference: https://docs.tibco.com/pub/doc_remote/sfire_dev/area/doc/api/TIB_sfire-analyst_api/Index.aspx

Tibco Spotfire Developer documentation: https://docs.tibco.com/products/tibco-spotfire-developer