I'm not sure about how to do it with the filter, but using the search box you can do the following:
for questions that have answers posted (even if none are accepted)
this will return results that have at least 1 answer. You can change the number to find questions that have more answers too if you wish.
for questions that have ...
I am not sure where you took your screenshot from but to see the Newest questions on our Main site I use https://gis.stackexchange.com/questions?sort=newest:
Finding questions with the newest answers is harder, but for that I use https://gis.stackexchange.com/search?tab=newest&q=is%3aanswer:
Getting the latter is harder than what I would like so I made ...
To do wildcard searching just type
into the search bar and you will see it expand to
In the type-in field at the top I always paste the URL to the duplicate rather than its title.
I had not noticed the suggestion that a search could be used, though.
Rather than a bug I think it is an in application documentation error but the bug tag on this should attract the SE developers to clarify whether the search option is expected to work.
I am not sure of the value in trying to treat tags as if they are optimized for search.
From What are tags, and how should I use them?:
A tag is a word or phrase that describes the topic of the question.
Tags are a means of connecting experts with questions they will be
able to answer by sorting questions into specific, well-defined
I think you should participate in Providing Search Option to Limit to questions placed by active users? , the question you identified, at the Meta Stack Exchange which is for all SE sites because, to provide the functionality you seek, it appears to need an enhancement that is wider than GIS SE.
Edit in response to OP's clarification in comment (but the answer is off-topic, now).
The reason why QGIS algorithm parameter can't be flagged as duplicate from QGIS Processing - Additional Creation Parameter for GdalWarp is because the latter is not an answered question.
In Stack Exchange an answered question is considered the ones with at least one ...