For our purposes, we maintain and translate a database of articles about several technical procedures in two different languages, because our service serves two different languages.
Currently, our german users can directly look up german articles, and our french users can look up the french articles.
If they wished to only display articles in certain languages, then they can create an account and set a Content languages option.
However, if we were to fuse the current german articles into the french ones, then german users wouldn’t be able to search the information they require, because while a singular post can be translated in any languages, you can’t lookup this topic if you don’t know the original title, leading to a worse experience than our forum currently offers.
For instance, I can’t find this topic using the localized french title - so, were I to only speak french, I wouldn’t be able to find it.
As explained by falco in the first answer, this is not a feature planned in the short term, and I understand why.
However, having the ability to filter/hide topics based on post locale would allow a good search/browsing experience for multilingual forums still.
Thank you still for the addition of post localization, both manual and automatic, as a feature and for your continued work on the Discourse software 