No, I haven't tested it. I'm just trying to pick the low hanging fruit first.
I think you need to learn how to use languages a little bit better first, before you continue to troubleshoot this flow.
First up, multiple language support comes in two varieties:
1) The language folders you define in the Document and Prompt repositories.
2) The languages pre-loaded in the system for IVR type prompts, such as the built-in prompt "Are you still there?" on the Menu step.
French and English are both supported languages, so you shouldn't have any troubles with this.
https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cust_contact/contact_center/crs/express_compatibility/matrix/uccxcompat11_6_1.html#Supported_Languages
Next, you should understand how the language is set for the caller. The Trigger has the starting language for the caller, and then once the call is in the script, you can change the language with the Set Contact Info Step.
Next, you should know how the system selects the Documents and Prompt, based on the language of the caller. There is a search hierarchy that the system goes through. So, as an example of en_CA, say you we're playing the prompt P[LQ_ADMINISTRATIF-M1.wav], the system will try to find the file LQ_ADMINISTRATIF-M1.wav in the en_CA folder first, and if it's not found it will then search in the en folder, and if also not found, once last attempt to find the file in the default folder will happen. If nothing is found then the default behavior is to skip playing this prompt.
So, if you do not have your WAV files in all of your language folders, then you will not hear any prompt on the main menu for English. Is that what's happening?
By the way, it doesn't look like you need the pThis = Create Container Prompt step, as it looks like all you are doing is trying to set the language, but like I said, the language is set on the Trigger and/or within the Set Contact Info step. You'd only need to use this method if you wanted to override the language for one specific prompt.
If your problem is in the subflow itself, do note that the language variable doesn't need to be passed around, because the caller has the same language set in both the main script and the subflow script. If you need to have a conditional statement based on the current language of the caller, you can simply retrieve the current value from the Get Contact Info Step.
So, therefore, in your subflow, unless you call it directly as well as use it as a subflow, you wouldn't need to Accept and Set Contact Info in this script, since those actions are handled by the main script.
In fact, it looks like you're trying to play the TTS prompts for Fr/En to enter the name twice: once in the main script before the subflow, and once in the subflow right at the top. Did you intend to ask it twice?
And if your problem is with TTS, I have no idea what's going on with the TTS stuff you have here, so I wont be able to help you there. I'll assume this is correct, since you claim it's working for French.
TTS["""\u001b\\voice=Carol\\ """\u001b\\rate=92\\ """\u001b\\vol=92\\ """\u001b\\wait=3\\ Please enter the lastname, followed by forename.]
