Somewhere between audacious-plugins-2.5.4 and 3.2.2, Audacious-SID lost the availability of its Preferences and About menus. That is, in Audacious 3.x, one can no longer modify SID emulation settings and/or set the location of a HVSC root directory / STIL / Songlength database (with its benefits).
Report upstream. There's no code in this plugin for those two features - chances are. though, the change was deliberate.
I see. Thank you.
Closing for now. There were a ton of architectural changes between audacious 2.5.4 and 3.2.2 and SID prefs/about may have been one of the lost components. It may be back in audacious 3.4, but if was important you you, feel free to mask newer audacious(-plugins) releases. I plan to keep at least 2.5.4 in the tree for quite a while longer.