[IMP] themes_*: rewrite some messages and fix typos

Themes translation in Odoo 16 have been lost, they were not exported on
Transifex anymore (bug).

We just added back the repository on it, and our internal translators
are working on those translations.

They found some typos and bad wording which are fixed here.

Technically, note that we need the themes fully translated for the
chatGPT integration coming in website configurator.
Indeed, if a theme is not (almost fully) translated, it won't be using
chatGPT for text replacement.
This is because if we ask chatGPT to do text replacement and translation
at the same time, it just provides bad results.
See https://github.com/odoo/odoo/pull/137703

closes odoo/design-themes#717

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

theme_clean/views/snippets/s_cover.xml

@@ -20,7 +20,7 @@
         <b>Sell from your couch</b>
     </xpath>
     <xpath expr="//p[hasclass('lead')]" position="replace" mode="inner">
-        Make your finances reach a new level with our online management system. <br/>Track every penny, directly from the confort of your home.
+        Make your finances reach a new level with our online management system. <br/>Track every penny, directly from the comfort of your home.
     </xpath>
     <!-- Remove the button -->
     <xpath expr="//p[2]" position="replace"/>