Hello RodWard,
Thank you for your answer. Apparently, after debugging a bunch of errors and tricking the system I made it work. 
No JSON is required.
For those who are interested in the process, here is a high level step by step explanation:
1.Create Project in Captivate
2.Publish it in HTML directly to a folder on sharepoint (you can get the folder path by opening the sharepoint library in IE then choosing View in File Explorer option. Right click on the folder, select Properties so you actually get the server path. I also published the package onto my local drive for faster editing after publishing onto sharepoint. It is important to publish directly to a document library because copypaste sometimes changes folder names and stuff.
3. Open the index.html file of the training, and edit the references to the assets (picures, js, css, etc...)
4. Replace the original index.html with the updated one on sharepoint.
5. Create a page on sharepoint that supports the addition of content editor webpart.
6. Link index.html to the content editor (watch for weird characters in the URL such as (sites/:r/:l) and any reference to line items in folder at the end of the URL.
7. Save it
8.Cry, because it will not work
And here comes the funny part:
9. I realised that the Sharepoint my company is using configured in a weird way, and it disregards subfolders when reading the links.
For example, a picture from the project was stored on .... sharepoint.company.com/sites/SiteName/SiteAssets/ProjectName/Published/picture.png
the references in the JS and HTML files were also the same, but when I saved the content editor, a 404 error was thrown with the following message:
Picture.png was not found bla bla, and the path were it was trying to find it was
sharepoint.company.com/sites/SiteName/SiteAssets/picture.png
Notice that the ProjectName/Published/ subfolders were not taken into consideration. Again, every reference in the project files were correct, but sharepoint dropped it for some reason.
10. I moved the missing file to where Sharepoint was trying to look for, and suddenly it was working.
11. I then moved the previously missing files to ther ORIGINAL location without changing anything in the references in the code, refreshed the page, cleared cache just to make sure, and it was still working.
Optionally you can put the training in an iframe on a modern sharepoint site where content editor webpart is not available to make it appear. (But you must have the actual project to run in a content editor, then link it into an iframe).
Hope it helps someone
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