First of all, words wisdom. There may be other ways to do this I'm not Git guru I'm just a guy that need to have things done quickly to reach my goal.
This was a kind of side and distracting but necessary action so I took the road and fix the issue.

How I get into to the issue

When I setup a Tiki CMS Groupware or any other project instance for production, I clone only what I need to avoid dragging a 5gb project on the customer infrastructure.
I use the git clone command as explained on some of my Tiki Express tutorials I "download" only the last code (not all the different alteration and comments) for a single branch (not all the repository).

So, after updating a Tiki (this one) from Tiki version 23 to Tiki24 and testing it I found some new strings that weren't't translated yet in Hebrew.

During a release process code should be first committed to master then cherry-picked to the branch(es) you choose. More details here.
Following the guideline of the Tiki Wiki Open Source development coders community I committed and merge my changes to master. Once done I tried to cherry-pick the merge to the branch Tiki24 using Gitlab tools. I went to the merge page and under the "Options" dropdown selected "Cherry-pick". This opened a modal to allow me to select the destination branch and I selected 24.x and submit.
But the feedback was not the one I expected as I did this before in the past many times;
_Sorry, we cannot cherry-pick this commit automatically. This commit may already have been cherry-picked, or a more recent commit may have updated some of its content._
After checking and retrying I understood I need to cherry-pick locally.

What was the problem

As explained above, my setup has ONLY the master branch and is not even aware of other branches.
So I had to modify my git config manually to allow git to fetch other branch than the one in the config.

How to add other branches when you deliberately cloned a single one

I went into project directory and edited the git config file;
nano .git/config
There I search the part that define the origin;
-+
[remote "origin"]
url = git at gitlab.com:bsfez/tiki.git
fetch = +refs/heads/master:refs/remotes/origin/master

+-

I replaced "master" for wildcard "*" on the fetch line
fetch = +refs/heads/*:refs/remotes/origin/*
I fetch the repository to refresh the useable branches and get all the branches
git fetch

$ git fetch
Enter passphrase for key ........: 
remote: Enumerating objects: 722113, done.
remote: Counting objects: 100% (660075/660075), done.
remote: Compressing objects: 100% (129034/129034), done.
remote: Total 652645 (delta 520308), reused 649762 (delta 517852), pack-reused 0
Receiving objects: 100% (652645/652645), 2.97 GiB | 5.86 MiB/s, done.
Resolving deltas: 100% (520308/520308), completed with 4409 local objects.
From gitlab.com:bsfez/tiki
.../...
 * [new branch]            16.x                                             -> origin/16.x
 * [new branch]            17.x                                             -> origin/17.x
 * [new branch]            18.x                                             -> origin/18.x
 * [new branch]            19.x                                             -> origin/19.x
 * [new branch]            2.0                                              -> origin/2.0
 * [new branch]            20.x                                             -> origin/20.x
 * [new branch]            21.x                                             -> origin/21.x
 * [new branch]            22.x                                             -> origin/22.x
 * [new branch]            23.x                                             -> origin/23.x
 * [new branch]            24.x                                             -> origin/24.x
 * [new branch]            3.0                                              -> origin/3.0
 .../...


After that I was able to switch branches and work on Tiki 24.x

Epilogue; back-porting manually using phpStorm

To develop and maintain my Tiki instances I'm using phpStorm .
In phpStorm I checkout Tiki branch 24.x
Open the Git section, selected my commit and cherry-picked... but there too it failed.
Seems something added in the code between the little time I rebased my original files version and merged my changes something was changed.

So from the branch Tiki 24.x I checkout a new branch "Hebrew_translation_24x".
Then I switched back to the branch Ithat contains my changes, "Hebrew_translation" and, in the phpstorm, I compared my file version and the branch 24.x version.
Using the merge tool, I manually merged the string that were newly translated.

Then I pushed back the branch "Hebrew_translation_24x" and merged it with the Tiki 24.x branch following the instructions you can find on my Tiki Express tutorials about development in Tiki and https://dev.tiki.org/Git-Workflow

If you are still reading I guess it helped you in some way and that's important to me.
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Be seeing you !
Bernard