Is Synfig Core 0.62.02 and Gtkmm 2.4.8 needed with Synfig Studios 0.63.05?
Not needed. The packages that we provide contains all the needed libraries.
and surely Synfig Core 0.63.05 must be used with Synfig 0.63.05 even if you have passed good time with your’ 0.63.02 core
related to configure.ac ; it’s gtkmm-2.4 who is shipped with Synfig.