That's different thing. Attachments (which were bound to posts) have been restored. All of them I believe.
However attachment URLs have changed, and links manually embedded in the posts haven't been updated. But if you correct them by hand they'll work.
With the exception of the ones that are orphaned - when original post to which the attachment was bound have been removed (or attachment was manually taken down). In such case these files haven't been moved to the new CDN.
The example of it can be attachment in the signature of DrSuperEvil (which is trimmed btw.) - full signature can be seen in WaybackMachine: https://web.archive.org/web/20160612001107/http://www.sc2mapster.com:80/profiles/DrSuperEvil/
That's the URL: http://www.sc2mapster.com/media/attachments/15/252/Screenshot2011-04-17_09_16_21.jpg
It uses old pattern. Now attachments are stored in CDN, corrected link would look like that: https://media.forgecdn.net/attachments/15/252/Screenshot2011-04-17_09_16_21.jpg
Unfortunately it doesn't work because of the reason I've mentioned above. It was an orphan. The post/project to which it was bound have been removed before site was migrated.
When it comes to links in general, then yes. They didn't bother fixing them. But it's fairly easy to do that manually using search engines when there's such need. As example take the link in DrSuperEvil signature: http://www.sc2mapster.com/forums/resources/tutorials/20772-data-actor-events-message-texture-select-by-id
Now cut the part after ID, that's: "data-actor-events-message-texture-select-by-id"
Then build following query for the Google engine: site:sc2mapster.com inurl:data-actor-events-message-texture-select-by-id That would be: https://www.google.com/search?&q=site%3Asc2mapster.com+inurl%3Adata-actor-events-message-texture-select-by-id
It works in most of the cases. If however title of the thread was changed, then other methods must be used.
This is how I've fixed links in the Tutorials section of the Wiki btw. https://sc2mapster.gamepedia.com/index.php?title=Tutorials&curid=496&diff=13382&oldid=13381 (using script that automated the process).
This is how I found it: site:sc2mapster.com "Screenshot2011-04-17_09_16_21.jpg" -"15/252/Screenshot2011-04-17_09_16_21.jpg"
(in Google) then in source code of the first result search for: class="multi-file-upload-file-image comment-attachment-image" alt="Screenshot2011-04-17_09_16_21.jpg" The preceeding src attr of img element will be correct URL. But I'm unsure if this method would work for in all cases. I think it's worth to note anyway.
(btw. this would have been easier if media.forgecdn.net was indexed by Google, but it isn't sadly).