The Lien ("link") template is troublesome, too. It hasn't changed in three years, so either it has been troublesome for all this time, or something has changed recently in how Parsoid or CX handle this template.

Portuguese Wikipedia has a corresponding template, and both languages have TemplateData, but the parameter names don't appear to be mapped to each other. Portuguese has numbered parameters (1, 2, 3), and French has named parameters (langue, trad, fr). I sometimes decide to be bold and just edit TemplateData in other languages to get the parameters mapped, but I'm reluctant to do it this time, because these are often-used and sensitive templates. Experienced editors in French and Portuguese should take a look at this and try to harmonize them.

But despite all the general trouble with how templates work across wikis, which I described above, I still wouldn't expect CX2 to behave so strangely and show {{{2}}}, etc., in the translation column. So I do suspect that something in CX or Parsoid is not working as intended.

2- translate the first paragraph using MT

From the screenshot I cannot see which MT system is used. Is the issue happening with all translation services available or only with specific ones?

In T259942#6371909, @Pginer-WMF wrote:

2- translate the first paragraph using MT

From the screenshot I cannot see which MT system is used. Is the issue happening with all translation services available or only with specific ones?

any MT engine, even with "copy"

I've taken another look at it today. It looks like this French template accepts parameters written in the French language, and the template's internal code converts processes French month names. Unfortunately, this cannot be easily translated and converted into Portuguese or any other language using current MediaWiki and CX functionality.