> P.S. Also, it seems that xcb-boomshine.el file doesn't correspond to its compiled version. For example there is no xcb-boomshine-new-game function defined
That may be a side-effect of using Emacs 27.1 as the file is using the shorthands feature introduced in Emacs 28.1. If the feature is not available, the identifier would be boom-new-game instead.