Learning another language will not cause speaking problems or worsen speech. Instead, it will broaden one’s horizons and provide countless benefits. It is inevitable that a person will be dominant at one language more than others, however both (or more) can proceed to be effortlessly used.
Personally, I am a trilingual person: French , English and Arabic were taught in school and university. I attended a French school until high school graduation. Then, I graduated with a Bachelors degree in Arts with a double major in French and English. I chose French because it has a smooth out-drawn sound that is lovely. I grew up loving that language more than I expected, and even teaching French to all grades for 14 years. I am happy to pass on my love languages to students as part of the Aux 3 Pommes team!