I started self-learning programming from Swedish resources, using Swedish variable names and (trying) to store Swedish text in databases. The good news is that I learned about encoding and how to store "åäö" properly early on, the bad news is that it was really difficult to ask questions on Stack Overflow when your PHP is 50% Swedish and 50% English. Actually entering the code into Notepad++ was difficult too, weird finger movements to get to the common "special" characters.

Since them I've moved to US keyboards after starting to work with others in an office and not being able to pair program otherwise, and obviously default everything else to English too.

I'm not a native English speaker, but when I come across that sort of "programmed in the country's language" programs today it does take some time to get used to the style and translating stuff while also trying to understand the logic. I wouldn't say it's a huge time-sink, but particularly names can be difficult to convert/translate on the fly when you're trying to get product and developers to agree to what we're talking about.