This may have been resolved, try installing this and reopen konsole:

sudo eopkg install https://packages.solus-project.com/unstable/p/plasma-desktop-branding/plasma-desktop-branding-1-5-1-x86_64.eopkg

Not solved

Well it fixed the display of many of the characters...will have to take a look

@mmeinert, can you run env | grep LANG in a terminal and paste the response here?

@folcred sure

LANGUAGE=fr

Hmm... I believe there should be two settings returned, one for the language, another for the character encoding. On my system it looks like this:

LANG=en_US.UTF-8
LANGUAGE=en_US

You could try entering the following in a terminal:

sudo localectl set-locale LANG=fr_FR.utf8

That would set the global environment variable for character encoding to French. You would still need to log out and back in again for the environment to be loaded, but it should help.

It seems there's been quite a few problems with the default character encoding, hopefully it will get figured out and fixed so it doesn't hold up progress on a final ISO.

I tried but it doesn't changed a thing.
After a reboot I got the same output

LANGUAGE=fr

I don't know if the problem is the environment setting isn't being read, or if the wrong location's being searched for it. Doesn't seem to be a problem on the other ISO's. Obviously something's different with Plasma or the ISO, but what and where is going to take some digging.

If it's only affecting Konsole for you, you can set it in Konsole's current profile. Right-click on it and open "Edit Current Profile...", then on the first tab open the Environment setting. Add to it:

LANG=fr_FR.utf8

Apply it, then close Konsole and open it again. That should at least cure it for the time being in the terminal.

Editing the profile did the trick ! Thx @folcred
Let's dig to make the release better ;)

Okay @mmeinert, I found where the problem lies, but still not what's causing it. There are two files that are used when Plasma starts that are suppose to set the locale environment variables. For some reason they're not being set, and one of them is a shell script that isn't getting it's executable bit set. They both are in ~/.config. The first one is plasma-localerc, and is now set like this for mine:

[Formats]
LANG=en_US.UTF-8

[Translations]
LANGUAGE=en_US

I think the main issue is the UTF-8 bit. You would need to replace whatever's there with your French language one.

The second file is plasma-locale-settings.sh, and the important parts are:

export LANG=en_US.UTF-8
export LANGUAGE=en_US

Again, you would have to set them to French. Then go to the file properties in Dolphin, and in permissions set the file executable.

These files are referenced by /usr/bin/startkde when Plasma loads, and startkde sets the user's environment locale. For some reason they're not being set properly. Why still has to be figured out. But without them being set, apps like Konsole and the text editors won't have the right encoding. This is a workaround, but it will get the system using the right settings for the time being. You'll need to restart Plasma for it to take effect. Then you shouldn't need the setting in Konsole anymore.

I created a couple of VM's to test on, and yes, the chosen language during installation is being set in /etc/locale.conf. However, once you change the settings for languages in System Settings, when you reload the session the default settings are no longer being honored. The user's settings take over, only they're not set properly.

I think I found the reason for this @sunnyflunk. It's a known bug in the way languages are being set now. There is a fix that has been accepted, but when it will roll out I don't know. Soon if not already I hope.

@sunnyflunk, I can confirm the patched update is working. Created a new VM this morning when the latest update sync hit. Made no changes after install to the virtual machine, and ran updates, then rebooted. Went to System Settings > Regional Settings > Language and chose my language. After clicking "Apply" I opened Dolphin and checked ~/.config/plasma-locale-settings.sh and plasma-localrc, both showed the correct uft-8 setting. Rebooted again and checked env in the terminal, everything is correct.

Will note though, if you choose a language and don't hit "Apply" before leaving that dialog, the setting won't be changed. Normally Plasma asks you if you'd like to save the settings when you've changed something and try to leave the dialog. For some reason that's not working on the language dialog, so user's should make sure they clicked on "Apply".