Hi! Regarding the file I/O issues, I have been developing chemfiles to help with this issue since 2015. It is not a pure Julia package, since all of the I/O is implemented in C++ with a C API (code here), but there are Julia bindings (documentation here). We already support more than 20 formats, and we are adding support for new formats regularly. The code is also quite optimized, see some or our benchmarks here, and benchmarks by other people including Julia code there.
I think that the code being written in C++ and thus accessible from more languages is a strength for chemfiles, since developers using C, Fortran, Python, Julia, Rust, … can use it as well. This mean bugs are discovered faster, and multiple language communities can share the maintenance. The downside of the code not being written in Julia/Python/… is that it make it harder for folks from these communities to contribute.
I’ll try to join the BoF session to discuss all of this, so see you there!