A possible reason as to why mobile menu is not working on http://residenciadonperro.com/pruebas is because you are using latest version of Cornerstone 3.0.4 in conjunction with old version of X Theme 5.2.5. I suggest you to update X Theme to latest version 6.0.4 and that should fix the problem that you are facing.
On the other hand upon checking http://residenciadonperro.com/, I see that you are using relatively old version of X and Cornerstone i.e 4.6.1 and 1.3.0 respectively. So far it’s good that you are not facing any issues. However, please note that running old version of Theme and plugins can cause compatibility and security issues.
I am sharing few resources from our knowledge base that you can take a look to update theme and plugins: