Wrong and ignored language to be translated My website is by default in French and I need to get an English version. 

Prob n°1 : I've got this kind of Exposed filter (exported in a block), everything in it is translated excepted "Tri" (sort) and "Appliquer" (apply) which stay in french.



Here, you can see all modules about languages/i18n (add i18n, i18n_block)



In my exposed filter settings (in FR) :



In the view, translate view > English > traduire > and I wrote this



In Config > Regional > Translate I found what I wrote correctly



Answer n°1 : Why my exposed filter labels can't be translated ?

Answer n°2 : Another thing, it's maybe common but I found this strange, when I write a sentence in t() function, it must be in english and not in my site language else I get



Is it normal to write in english in t() function even if the site language is not ?

Thanks in advance for helps. I'm listening some tricks, advices and good practice about languages.
First, you need to select source/default language from admin/config/regional/language.

After you need to import .po file of English or your selected import other import languages (https://localize.drupal.org/translate/languages/en).

Now you will able to translate your term from Config &gt; Regional &gt; Translate. and those are visible according to your language.