I hate using certain apps in Spanish, and VS is one of those. I prefer using it in English, and as the installation takes ages, I decided to switch the UI language instead of uninstalling and installing all over again (which would be cleaner, I guess).
First problem is that VS only comes with one language: the one you chose when downloading. So, no English available…
So, I decided to search for a language pack, which is quite easy. The second problem is that the official MS link for that always seems to download the Spanish language pack. No matter what. Please note the installer says “Paquede de idioma 2015 – ESN” instead of “2015 Language Pack – ENU”:
Third problem is that if you try to install the Spanish language pack, it won’t detect that VS already includes that language, and will go through the whole installation process (and wasting hard drive space, I assume). It’s completely useless, as VS already has that language, and as a result VS Internationalization Options will remain the same.
So, if you want to download the proper lang pack, use this other link instead. It will provide you with the correct installer. After using it, now everything is working as expected, and it's installing the proper Language Pack – ENU.