To everyone interested:
Hej there, in the past few months I have been writing up my experiences with uploading many observations to iNaturalist at once using the API. I have written a Medium story to show the source code and explanations on how to do it:
All observations that I uploaded with this script are from botanical research, so for that I followed the protocol outlined in a recent paper. In the scripts as you will find them now online along my blog post I used real data from a biologist colleague, so that it may be a good entry point for you to customize your scripts. There will always be additional steps required to customize the script to your needs though, I guess. I would very much appreciate any feedback, comments and suggestions on the blog post.
If you are trying to follow along the scripts and encounter some problems let me know and I can try to consult in your project.