The change of the new forum seems to me that it has not been professional and I explain why.
Yes correct old links don’t work anymore as the official Discourse migratioin script simply generated new topic ID’s. We are aware on this and we deceided to keep it as is. Otherwise it would be a couple of thausend redicted we would have needed to created. And we did not find a soulution for this. Next to this, it is nearly impossible to change all URL on all platforms. However the search function on Discourse is quite good and you should find any topic.
As well all usernames are migrated to Discourse as they are. Of course the password would need to be reset bevore first login on Discourse. I could have a look to your old user name if you could send me a PM.
As well we tried to reset all search engines to point to new forum url. The result proably depends on the search engin used. I see your example is done with duckduckgo. Could you try some other search engine like Google?
Sadly only Google allowed me to remove the old URLs from the index, the others are overriding the admins aim when they think these URLs are important. Sitemaps have been updated, the ones for phpBB removed and new ones for Discourse transmitted, so this is all we can do. The search engines chose to find out themselves gradually that the old links are invalid (redirected) . Let’s see how fast their crawlers are.
you know duckduckgo will sell your info as well. don’t use it because of any safety over google. (*there is none and you get weaker searches lol)