@yoBARBZ So far the only old evolving buildings it was possible to obtain artifacts for have been the Phoenixes and the Bears. During the Coldfire Phoenix event, it was possible to convert Coldfire Phoenix artifacts into regular Phoenix artifacts in the Magic Academy. The ratio was 2 Coldfire artifacts to make 1 regular Phoenix artifact. The exact same option was given during the Moonbear event, where you could convert Moonbear artifacts into regular Bear artifacts at a 2:1 ratio.
I would also note that in both cases, the original Phoenix and Bear buildings were added to the crafting rotation so new players could make them. I think it is unlikely that Gingerbread Mansion artifacts will ever become available again. But if I am wrong and they do, the base building will almost certainly also be available.