Hi There,
I believe this project can be completed in lot cheaper, or there is no immediate solution. I wanted to quote less but it is restricted.
Regarding myself, I provide Moodle eLearning environment to large educational institutes and have been working in this space for more than 10 years.
Last month, I spent weeks to troubleshoot unoconv issue as some of my clients hugely depending on it for annotation.
I am keen to look at your affected file if that is not confidential.
Also, if you could share what version of Moodle, unoconv, libreoffice, OS and OS version would be helpful.
Cheers
Sij