Hi maximillion,
Sorry for this lately reply.
Firstly, i checked the SRAM of S32K142, i think your address of SRAM_LOWER_START_ADDRESS is matching with size of LOWER, so the Heap region will continously from LOWER to UPPER. So i don't think the address of your SRAM in any problems.

Secondly, about m_data_2 i can't find it in linker file of S32k142, did you using GCC or IAR compiler?
Can you share your using linker file?
I will as OS team about this issue for more investigation, so it's really helpful if you can share to me the error log and details of package that you're using now.
Please let me know if you have further information.
Thank you,
Nam.