WadSmoosh is written in Python so if you're running it "from source" (which is what that shell script does) you'll need Python installed on the system. I've never used ChromeOS before but it looks like it doesn't include Python out of the box.
Try typing just this at the terminal:
python
and see what appears next. If that actually launches the Python interpreter, quit out of it and type
which python
If that returns a path (eg /usr/bin/python) then try running
python wadsmoosh.py
from the directory where you have WadSmoosh.
Let me know what each of those commands result in. Like I said I don't know anything about ChromeOS specifically but if you're able to get a reasonably normal Linux environment, running programs in python should be straightforward.
I have attached a screen grab of what I see when I run those commands in terminal + other weirdness and from what I know linux runs in a container but google uses the words VM as well to describe it so your guess is as good as mine, I am only on this because well my main laptop died this week and for the foreseeable future this is all I have.