Butler XT2 uses e:bus with old Glass Touch devices (like GT T6, T12, T6R). All these products are EOL.
Butler XT3 uses e:bus2, which is NOT compatible with e:bus. Thus, old Glass Touch devices (like GT T6, T12, T6R) can NOT be used with Butler XT3. Compare XT3 manual.
Butler XT3 is supported by LAS V7.0 SR3, available on our download page. Direct link: https://eu.traxon-ecue.com/products/lighting-application-suite/attachment/ecuelightingappsuite70_sr3/