Rename "Submit" buttons

I don't think "Save" is the right word here. As a user, I'm not "Saving" a submission, I'm "Submitting" it to the site. This is different than nodes, in which you're creating content. In Webform, we even call them "submissions" so by clicking the button you're creating a submission, hence "Submit" is the right terminology.

Save survey?

You can't really put a noun in here, other than maybe "form" or "submission", because not all webforms are surveys. A lot of people use webforms as a contact or support form for example, so making the default label include "survey" would make an incorrect label for a lot of forms.

We also should avoid "Save", because after we add the feature at #290448: Only email results, don't store results on the site, you won't be saving anything. You'll just be "Sending".

In all cases, I get the feeling that if you want a specific (accurate) label, you should just use the UI option for changing the label (under the Webform -> Form Settings tab).

Aside, how are webforms translated?

Webform provides hooks for altering just before fields/labels are displayed, and every element has an array of translatable properties. Combined, it makes it so that all the information is available to make translation possible. Webform itself doesn't provide an UI for this, instead it's handled by webform_localization.

However the more common thing is just to translate the node using the standard core Content Translation module, and just simply have different forms for each language. The Webform Localization module is only used when it's important to aggregate all results across languages.

In the case of the submit button, I think we just cheat and run it through t(). So whatever label a user enters in the UI will be translated via Locale module.