Instead of posting a link to a “raw” file that then needs to get loaded and processed by a function you could make it easier for the other side and dump the final matrix, i.e. xsim[:idx] to a reasonable file format that can be read directly. For example, using NPZ.jl which is compatible with numpy.save and numpy.load.
This way you can simply load the file in Julia and Python (i.e. numpy) and assure that you actually operate on precisely the same data.
(You want to abstract away your context as much as possible when creating a MWE.)