OJS3: uploading submission files in multilingual installations: does the file name have to be localized?

Hi @asmecher, @bozana, @ajnyga and @NateWr,

i am having EXACTLY the same issue as reported by @ajnyga
I am running OJS 3.0.2 (upgraded from 2.4.7 in early July 2017 with the 3.0.2 .tar.gz package available from PKP website) with French (fr_FR) as primary and English (en_US) as secondary language (actually, I also had fr_CA initially, but deactivated now although it still appears on the language settings screen).
Both languages have all functions activated (UI, submissions, forms), since we have both French and English readers, editors and authors.
The journal accepts submissions in either English OR French, and submitting in both languages is NOT required.
I have tried to read through https://github.com/pkp/pkp-lib/issues/2114, but it is a bit too long and complicated for my skills.
My question here is: what’s the solution to this issue, if any?
Are they any clear and strait-forward instructions I could follow?
Can you confirm I have to check/change the 10 files indicated here: pkp/pkp-lib#2114 submodule update ##bozana/2114-stable## by bozana · Pull Request #1290 · pkp/ojs · GitHub AND 1 files here: Merge pull request #9 from bozana/2114-fix · pkp/quickSubmit@70d039e · GitHub
???

By the way, I am also experiencing the same issue exposed here: Submission track names of files - #30 by knjigor and got lost too in trying to figure out how to fix it.

It is a bit odd that I upgraded from the PKP website’s package AFTER the two mentioned issues were reported and apparently solved on Github. Could it be that the package I downloaded is not in line with the one available on Github?
In any case, where could I start solving at least one of these two issues?

Thank you.

Axel