For the error message /usr/bin/env: ‘python’: No such file or directory, TagUI will run the command python if it detects that Python is used in your automation.

Via ros/urdf_sim_tutorial#7 With Ubuntu 20.04/noetic, @qboticslabs is having trouble with getting xacro to run Python code. This may go further upstream than xacro, but I'm starting here. $ rosrun ...

Cannot open a shared object no such file or directory occurs due to missing packages, but this guide can help you fix it in no time.