If I change my Google account's default language, it sets it for Search and Google Maps, and Gmail and so on...
Now I want my Search to default to one language and my Google Maps default language to be another one?
Is it possible to do so?
It's no possible because the language settings are managed for the Google account not for for those apps.
NOTE:
There are some apps that have some language related settings, like Google Search for the language for the search results and Google Sheets for the language for the functions, among others.
Reference
Yes, it is. The interface language of Google Maps is triggered here:
Language of Google products can be set up here:
While Google Search results are managed from here:
However, Gmail has its own language settings in:
side note: "Current Region" is derived either from your IP or your GPS