jai feels like a set of easy but not very deep sugar extensions around c. There is no big though story about aliasing, ABI and call optimizations in jai unfortunately. There are dozens of similar projects (V lang, caught caught, C3, ...) from authors frustrated by C but without stable foundation.
If Blow released it openly then I would consider it.
Last time I looked Jai was in a closed beta.
What exactly does Jai bring to the table?
Jai has no embedded support.
no 32-bit embedded support—as long as the target platform is 64-bit it'll work just fine for such purposes.
That's silly. Embedded developers rarely work on 64-bit target platforms. Much more common are 8-bit micros such as AVR or PIC with the 32-bit STM32 when you need more power.