There are certainly cards that work fine with both and it can be done but you will either have stuff that does nothing with one half of your engines or you will have a pretty underwhelming Sneak Attack compared to what it can do
And no, I dont mean a physical cube out of Magic cards, that would be quite silly
Theres nothing wrong with the deck or strategy, but its power is limited by its options much like Admiral Beckett Brass was before Commander Legends
Especially with Dragons Rage Channeler and also Ledger Shredder, Mishras Bauble still performs and synergizes very well with mentioned cards, being able to manipulate the library, making up for better draws, helping with Delirium and fueling the graveyard for earlier Murktide Regents
Why proxy it: High power level across multiple formats, significant price, and frequently required in multiples for cube builds
(8/7/2020) If one of the basic land types isn't present, it isn't chosen