My editor needed a change made to the French version of the Submission Preparation Checklist, because the “date and status” info was empty and could not be added. I searched the htdocs directory for “June 20, 2018” and found only one file: fc-journalSettings-8.php in the cache folder. That field for fr_ca was empty, so I added a wording there and the information now shows on the webpage.
However, I have a question. Seeing as this file is in cache, will that (and any other information) stay intact if the cache is deleted one day? Or should I be editing a completely different file somewhere?

It is edited via the Workflow Settings, under the “Submission” tab.
Changes are stored in the database, specifically in the journal_settings
table.
The data from the journal_settings
table is cached temporarily in the .php file you found in the cache directory. When the cache file expires, it is deleted and recreated from the database.

Thank you for pointing this out, @ctgraham!
My problem was that the 3rd line out of 5 (the middle one) on that list was not clickable and could not be edited on the web. After I edited the fc-journalSettings-8.php in Cache, this 3rd line was filled with what I put there. However, the journal_settings table has the “submissionCheckList” row for the locale fr_CA that still didn’t have the wording that I inserted into the php file.
It had the following:
a:5:{i:0;a:2:{s:7:“content”;s:180:“L’article soumis n’a pas déjà été publié ou soumis à un autre journal pour considération (ou une explication a été fournie dans la section des commentaires à l’éditeur).”;s:5:“order”;i:7;}i:1;a:2:{s:7:“content”;s:59:“Le fichier est en format OpenOffice, Microsoft Word ou RTF.”;s:5:“order”;i:8;}i:2;a:2:{s:7:“content”;s:0:"";s:5:“order”;i:10;}i:4;a:2:{s:7:“content”;s:185:“Le texte respecte les exigences stylistiques et bibliographiques du guide The Chicago Manual of Style. S’il y a lieu, des adresses URL ont été fournies pour les références.”;s:5:“order”;i:11;}i:5;a:2:{s:7:“content”;s:163:“S’il s’agit d’un article soumis à la section évaluée par les pairs du journal, les directives de la section « Ensuring a Blind Review » ont été respectées.”;s:5:“order”;i:12;}}
So, after reading your post, I went to the Paramètres du flux des travaux → Soumission → Liste de vérification de la soumission again. Since the edit made in fc-journalSettings-8.php was still showing, I was now able to edit that line. I changed it to “Test”, saved, then re-opened and re-pasted the French test that was missing and voila. the journal_settings table now has this:
i:2;a:2:{s:7:“content”;s:268:“La date et le statut de la soumission et de la révision sont notés sur le document. Par exemple : Soumission initiale : le 5 juin 2018. Révision conformément aux commentaires des examinateurs : le 20 juin 2018. Commentaires sur la révision : le 25 juin 2018, etc.”;s:5:“order”;i:14;}
instead of this:
i:2;a:2:{s:7:“content”;s:0:"";s:5:“order”;i:10;}
Case closed, thank you very much!