Should it be looked down on?

I think so. You don't know who might touch your code later, better to use English than for them to figure out what those words mean. It would be like using giberish for all your variables.

Another issue, even for other speakers of your language, we don't all translate english words the same, some words are just not translatable and some words look the same but mean different things, how can they tell if it was meant to be English or not?

For example in Spanish, "default" translates to "por omisión", two words, there's no single word for it, a lot of people translate it to "defecto" because it's similar but that means flaw, defect. It's so used, people say "por defecto" instead of "por omisión" now and some dictionaries added it as a translation already.

Another example, "cache", I know its meaning in computer lingo, the times I've had to use it is in the context of computers, so I have no idea what its translation to Spanish is or if there's even a word for it. If someone used the translation in code I would have no idea what I'd be looking at.

One more, "library" translates to "biblioteca" but some people use "libreria" (bookshop) because it sounds similar. You can find usages of both in documentation. People will probably understand both but it hurts searchability.

Well. Although this rouille thing is obviously a joke, it's also just a preprocessor macro layer, so it'd be pretty easy to switch to any view of the code. Could write it in "french" then transform it to english, then to russian.. Could also imagine doing that in an IDE without even impacting copy and paste just as a visual layer. Not sure what one would do for that spanish por omisión, but maybe just put an underscore. por_omisión

For another example of this, there was BritCSS someone made that lets you use British spellings in CSS:

https://github.com/DeclanChidlow/BritCSS