This is an extremely interesting project and I'm sad to hear your last freelancer couldn't help you find a solution, although you requirements are fairly vague. Would you initiate this software/code/app that would create you maps, or would they be automated. Should this software/code/app be launched via your phone, web browser or desktop application?
As I search for a solution it would help if i understood the end need/goal of the software/code/app then i could create a solution that adequately matches.
I've spent the last hour doing some reading on My Maps within google and there seems to be no clear way to easily create your solution.
Firstly, any calls to non public files within your Drive would require the use of Google APIs, this is not a problem although its important to now to that limits exits for the use of APIs.
Also at this moment in time My Maps cant not be downloaded from Google Drive and the editing of them is not available through the Drive API.
Lastly, My Maps to my understanding is an interface that allows you to share maps within your google Drive with other people, within the My Maps interface you can import data. My solution would include creating a script that formats your data into a form that is easily read by the MY Maps interface.
There are many other ways to tackle your problem although with out more detail I can't tell you which one is the most feasible.
Please PM me and we can discuss it in more detail.