Hi,
As Jerome said, you can change the translation key for these two.
So for example, instead of :
ORDER_CREATION_SUCCESS_ON_WEBSITE_AT_DATE="We are pleased to confirm the creation of your order No. %s at %s on the %s at %s"
you could add the override:
ORDER_CREATION_SUCCESS_ON_WEBSITE_AT_DATE="We are pleased to confirm the creation of your order No. %1$s at
www.mycolorsetmatch.nl/
on the %3$s at %4$s"
Now if you don't have the URL you want there, it means that you don't have the correct URL in the "live_site" parameter of your Joomla configuration.
Instead of overriding all the text and URLs in HikaShop, I would rather recommend to fix that setting of your Joomla configuration.
It will be easier, and will help for other things/extensions which rely on that parameter like HikaShop does.