Mixing an 32 bit library and a 64 bit toolchain is not likely to work!
Step 1. Decide if you wish to use 32 bit or 64 bit?
Step 2. If 64 bit, find or build an 64 bit SDL2 libraries.
If 32 bit, find an 32 bit GCC toolchain to use; and, configure CB to use it.
Edit: x86 means 32 bit; x64 means 64 bit.
Edit2:
https://github.com/libsdl-org/SDL/releasesEdit3: x86_64 means 64 bit, also.
Edit4: i686 means 32 bit, also
Tim S.