Hello Jordi,
I can help you out with this.
The Week Of Filter calendar normally does change to the day of the week set in WordPress.
I could not find a filter that changes that, but I did find the script.
In this file:
\events-calendar-pro\resources\tribe-events-week.js
That is what is building the calender.
It looks for information in this line:
<!-- Calendar Header -->
<div id="tribe-events-header" data-title="Events for week of September 7, 2014 12:00am | The Events Calendar Sandbox" data-view="week" data-startofweek="0" data-baseurl="http://events.jesseeproductions.com/events/week/" data-date="2014-09-07">
However, I did not see that in your template you are working on.
This is usually the line that creates those attributes:
<div id="tribe-events-header" <?php tribe_events_the_header_attributes() ?>></div>
See if you can add that into your template and it fixes the calendar.
Let me know if that works or you would like some more information.
Thanks