Hey again @oshyan.
So we looked into this and managed to build a scenario that works yet tends to be quite fragile and cumbersome.
You see, you get the text of the Discourse post which contains the URLs leading to the attachments and you need to retrieve the right URL. 
The other thing is that you don’t really know what kind of files you’ll be getting from Discourse. They will probably mostly be images but it does not have to always be the case.
We created a scenario that is capable of processing images coming from Discourse and sending them over to Twitter. It looks like this and it is definitely an advanced one.
If you’re familiar with Integromat and are feeling confident, we could DM you the blueprint of the scenario and you could tweak it based on what your attachments/posts will be. Just let us know if you’d be interested in that 
To learn how to import/export blueprints, you can check out the relevant section of this help doc.