Not able to access internal memory after setting SD as default
I am answering to my own question.
First of all,  on Huawei, SD Card support is very limited. You can barely use an SD to store files,  to save camera pictures, to store some app data in limited circumstances. Setting default media as SD Card does do not much of a change either. Since Huawei is not very open, they don't want you to mess with your phone's data, so if there is a memory card for data storage as an alternative, it prefers dedicating internal memory (the data.img file in the System Flash) to app data, which shall not be accessible by other apps, only by the app that is using the data. I think this is what Huawei would like as ideal configuration, but since not always you can use an SD Card, you also have the "all-accessible" mode.

Moral:
If you want to use an SD card with Huawei (for recording video, storing a great deal of music, having movies) NEVER tinker with default storage.
After setting default storage back to "Internal", ES and other apps are displaying Internal Memory as "0" and SD Card as "E43A-A70F". 
If device is rooted, you can create the needed symlinks and not even touch Storage settings.