Have you tried the WP REST API or the API included with Jetpack to post custom field data?
I can’t see any reason why this plugin couldn’t achieve what the OP wanted – with code. The idea is to extend WordPress – not provide a use case for every scenario. Reviews like this are truly unfair – I mean – because Person A wants to achieve Outcome X they give it a lower rating?
While I don’t think my original request was necessarily unreasonable, I did adjust my review of this plugin since I was able to find a conflict (which caused the original poor rating) in a subsequent project and successfully use this tool to pass data as needed.
I’d forgotten this review even existed. I do remember that other reviews existed here before – it’s a bummer that only mine remained after whatever purge happened.