It's the same for me when writing Swiss-style German. It's not only cumbersome to type the special characters like ö on a cell phone, also spell-check is a pain in the ass. For example, spell-checkers are not aware that in Switzerland, we do not use the ugly German ß and just write ss instead. So I get false corrections all the time. Furthermore, spell-checks usually seem to be designed for languages like English with only a limited number of flections. English only has singular and plural, but in German, the ending of a word can be bent in much more ways, making it rather unlikely that the spell-checker suggests the one you want. I suspect that most spell-checkers do not know that "car" and "cars" are the same word in a different form. Instead, they add each form to the dictionary individually. This works well for English, but for many other languages awareness of this would be helpful. Another detail is that expressions that are short in one language can be long in another and vice versa, so many direct translations of English words are much longer in German, taking more space on buttons and other UI elements, thereby screwing up the layout.

So yes, even when "localized", hardware and software is usually not fully adjusted to the language. And for German, which is relatively close to English, the problems are probably relatively small. I cannot even fathom how big all these issues for more distant languages must be.

And to answer you questions: yes, these pain-points lead me to sometimes prefer English and to avoid special characters. I even avoid spaces in file names as too many programs I worked with in the past struggle with that.