Please confirm the following points before you contact me. At first, I apologize that it is difficult for me to deal with your all issues because of my poor skill.
If you found bugs and have future requests in my published applications and scripts, please feel free to tell me. I would like to consider to modify and update them. In this case, please don't include the script that you modified from my script except for the variables of the file ID, filename and so on. Because I tested for only the published scripts. And, in the case of the bugs, please include the detail information for replicating the issue. If I can correctly replicate the issue, it will help think of the issue and solution.
I think that the change of specification at Google side and the library I use and also my mistake might occur. In such case, the publised sample script might occur an error. At that time, I would like to resolving the issues and upadte them.
I have to apologize that I cannot answer all your questions. When you have any issues of your script and project, I would like to recommend to ask them to Stackoverflow rather than directly contacting me. Also, when you have the issues of your Google Apps Script and Google APIs, I would like to recommend to ask them to google-apps-script of Stackoverflow and Google Apps Script Community. By this, many users including me can think of your issue.