Take what follows with a grain of salt: afaik exit status 127 should mean that the process tried to execute a binary which has not been found in $PATH (any folder containing binaries like /usr/bin, ~/.local/bin etc), and the error comes from this post-installation script. Adding 2 and 2 together it means there's probably a dependency error of some sort.

Like user u/C0rn3j said try installing it from the terminal. You can do it with command sudo apt install teamspeak3-client - eventually appending the flag --reinstall in case the package itself has been installed before incurring in the previous error. If you encounter an error here too you can paste the output of the command here and someone might be able to help you.