Mods currently do not work for MacOS as the mod system currently uses a crude text file parsing system(scripts/mods/modpanel.gd) to edit the files with matching relative paths. It will not report any failures during the application of mods, nor warn of conflicts between mods. Due to the fact that all the game's script files are stored in a .pck file for MacOS, the relative paths do not match and the appropriate changes are not made.
There have not been any recent changes that would break var reassignment. The "Faster pregnancies & growup" mod works fine for me (Windows 7 x64); the changes to variables.gd match the mod. If you managed to overcome of the .pck file issue, then verify that the mod folder is located correctly(Strive/mods/Faster pregnancies & growup/info.txt), as the mod system will only check the immediate sub-directory.
The community currently does not have any active MacOS modders, so we have not been able to overcome issues related to the OS. There is a Discord(https://itch.io/t/284398/discord) where we modders and players discuss stuff. I would appreciate any help you can give towards compatibility with MacOS. If you can find a method of modding the game on MacOS, then I can create a mod system for it.