You may ask if the second language can improve your thinking, or even your critical thinking. I think it may be possible so let’s consider what skills and dispositions can be improved if a person knows more that one language.
One of the most important dispositions is alternative seeking. With this disposition a person looks for other explanations, theories, facts, and pieces of information. The second language can help here in different ways. When a person studies another language, he usually meets another culture. Sometimes it is very close contact, sometimes a person only learns some facts related to language concepts. In any case these knowledge helps to look from a different point of view on well-known things.
Another way to look for alternatives is through foreign words and sentences. Separate words usually have different meanings in other languages: they may have a similar meaning like in your native language, but there could be other dissimilar meanings for the same translation. When you translate whole sentences the number of meanings multiples. You can be lost in translation or you can use this phenomenon to explore alternatives. For example, even thinking in another language can yield some insights. Finding synonyms, antonyms and associations can also help.
You can talk directly with more people if you know another language, and they can provide you with more alternatives or with something else. If you are checking sources you can use media on another language without translation.
With another language you will have more experience of transferring knowledge and meanings in different directions. It may help you to express your thoughts more precisely and correctly on any language you know.
Learning language is a deliberate practice, you also use different resources of your mind and learning to control how you use it. It means that language learning is a meta-cognitive activity, you can use it to improve meta-cognitive thinking in other areas.
And finally when a person learns another language and meets a foreign culture it may make this person more open for new and different things. Of course it may have the opposite effect, but there is a possibility for improving this particular disposition.