This issue is probably not related to the content Translation tool, but perhaps to the mechanism interwiki links are calculated.
Also compare the image below, to find a case where a page has been newly created on SEWP, and Interwiki links were later added.

No matter what is done: The interlanguage link for the wiki I am editing in should not be shown (either as missing or present, in any case).

If @Jpita finds a clear way to reproduce this error, we will try to trace and send it to the best project it fits.

Steps:

1. open article with missing translations
2. click grey link for a missing article
3. translate and publish the article
4. open the new article page
5. open the original article page in another tab

• The grey link shows correctly for the new page but not for the original one
• If we open the original page and add ?action=purge to the url, it shows the correct grey link after the purge

@Pginer-WMF is there any action we can do here?
maybe we can force the purge after a translation is finished, should be very straightforward.

In T199159#5356896, @Jpita wrote:

@Pginer-WMF is there any action we can do here?
maybe we can force the purge after a translation is finished, should be very straightforward.

If this is technically feasible it seems a good solution.
The problem seems to happen with enough frequency and for users noticing it creates confusion and may make them do additional unnecessary work trying to connect the page on Wikidata manually.

When article is published with Content Translation, we automatically connect to Wikidata item and do the purging, so that interlanguage links are updated.
That makes sense for newly created article. I don't think we should purge cache for articles in all other languages.

However, there is a different problem described in this task. Article was published to Simple English Wikipedia (which means it was target wiki and page got purged), but gray interlanguage link still shows Simple English as option. We have seen numerous problems around Simple English wiki and this is one of them.

I checked and the problem is still there. If Simple English is one of the languages determined (by the algorithm) to be one of user's preferred languages, it will be suggested to translate into, even on Simple English Wikipedia.

In T199159#5357908, @Petar.petkovic wrote:

When article is published with Content Translation, we automatically connect to Wikidata item and do the purging, so that interlanguage links are updated.
That makes sense for newly created article. I don't think we should purge cache for articles in all other languages.

Are we doing the purging on the target article or also on the source one?
It does not make sense to purge many articles, but I expect that the one in the source language may be the one more likely to create confusion. Does it make sense to purge that if we are not doing it already?

However, there is a different problem described in this task. Article was published to Simple English Wikipedia (which means it was target wiki and page got purged), but gray interlanguage link still shows Simple English as option. We have seen numerous problems around Simple English wiki and this is one of them.

Ok. Let's keep this ticket scope focused on the Simple English issue (I'll make it explicit in the title), and decide about whether a new ticket is needed based on the question above.

I translated 2 different articles from english to simple english and simple english to spanish and saw no issues.

In T199159#5360438, @Pginer-WMF wrote:

Are we doing the purging on the target article or also on the source one?
It does not make sense to purge many articles, but I expect that the one in the source language may be the one more likely to create confusion. Does it make sense to purge that if we are not doing it already?

We only purge newly published article (target article). That is achieved with one API call using action='purge', and it should be easy to do for source article as well.

In T199159#5360635, @Jpita wrote:

I translated 2 different articles from english to simple english and simple english to spanish and saw no issues.

Great. I'll close the ticket, then.

In T199159#5361211, @Petar.petkovic wrote:

We only purge newly published article (target article). That is achieved with one API call using action='purge', and it should be easy to do for source article as well.

I created a ticket capturing the idea. Not for immediate attention, but we can consider the idea if we observe more frequent issues like this: T228893: Purge source article after publishing a translation to ensure the update of interlanguage links