Dear Amir,
A1) I take note of your requested feature.
A2) Notice that if I don't replay the environment I may don't spot the problem.
I also take a note to test VPL with rtl languages. Please let me know of possible errors with this type of languages.
A3) Your information about where is the "download all submissions" link tell me that you are not using the last VPL version.
A4) No "execution files" may be useful if you don't have access to the jail server. Notice that new versions of VPL support binary files out of the box.
For installing complex tools, like new programming languages the correct way is to install it directly into the jail server. But any way you need to add/modify the script (vpl_run.sh, vpl_debug.sh and vpl_evaluate.sh) that launch this tools to run its.
Best regards,
Juan Carlos.