Linux version of the game is now a lot faster to start up on my system; before it took a few moments to load, now the splash screen shows up instantly. Thank you!
That said, the archive for this particular version came with permission issues ― a symptom of which is the four folders in the “IN HEAT_Data” directory would show up as binary files.
For anyone else running into this, my solution:
I lazily gave the data folder standard 755 permissions, and added the executable bit recursively (chmod 755 && chmod +X -R).
Alternatively, you can also copy the permissions from the last working version.
The permissions for individual files appear to be fine, I only had to change the permissions of the directories/folders.