Proposals are a means to share ideas and gather interest for new extensions. Extension developers are more likely to pick up proposals that have shown a lot of interest.
Proposals can also be used to crowd-fund an extension. In that case the concept should be well described and simplified as much as possible, so everyone can know what they are pledging towards.
Your request seems to describe a very particular use case that will likely not benefit many other forums. It also seems like most of it can be accomplished with existing extensions and features.
If all you need is the "glue" between existing features, there are 2 solutions: make a custom implementation using the Flarum extension API, or use an automation extension.
A custom local extension is quite simple if you can find a developer familiar with Flarum. Automatically creating discussions with custom text based on built-in events is very simple, and by writing the code you can make it work exactly like you want.
An automation extension would allow doing this without writing any code, but this in itself is a very complicated extension that requires a lot of coding. We currently have one such extension, Automoderator. Some users have found it lacking in functionality, and that's always the problem. No matter how advanced an automation extension is, there will always be use cases that cannot be satisfied. Funding the creation/improvement of such an extension is also likely to cost a lot.
I have no doubt that in the future more extensions will exist to automate actions and customize other extensions, but in the meantime a custom implementation would probably be the quickest and most cost-effective solution.
