For non-native English speakers, PMP Certification process may be a challenge.
As you realize, PMI’s webpage is completely in English. All the policies on the certification process, profile page, application forms, selecting a test center process, reporting PDUs, contacting PMI… All of these processes are in English.
But good news, PMI has language aid and states these languages in the handbook. Currently, language aid feature is provided for the following languages: Arabic, Hebrew, Brazilian, Portuguese, Italian, Chinese (Simplified), Japanese, Chinese (Traditional), Korean, French, Russian, German, Spanish, Polish, Turkish.
When you select the language aid, in the exam you will see all the questions both in English and in your native language. Even though you feel comfortamble with English questions or you studied from English materials, I suggest you choose language aid. There is no harm to choose your native language since you will have the question in both languages.
Even though there is language aid in PMP exam, I strongly recommend for you to improve your English if you don’t feel comfortable with your English proficiency. You never need to speak or write perfectly (I also do not speak perfectly), but understanding what you read and speaking fluently will make you succeed during your career.
As a project manager, you may work in global projects. Since you have PMP, people will assume that you speak English at least advanced level. Plus, there are many good sources in English. Even PMI has many books in English and they are free for the PMI members. I mostly use English sources while working, because I cannot find enough sources in my own native language.