The O.P's linked datasheet explicitly gives the wraparound sequences as annotations on Fig.8.
It also gives the cascaded counter configuration as Fig.17.
The 74HC193 is a 4 bit binary counter, it knows no negative (2s complement) convention, just 4 bit counts with underflow/overflow/ or carry/borrow if you like. It counts a range count of binary 0 to 15, all positive values. Negative binary numbers requires a different count method where the high order bit is a sign bit rather then a value bit and requires a different carry/borrow method.
You are mistaken. Consider 2x 74xx193 chips connected in the Fig.17 cascaded configuration.
Initially reset them to 0x00, with all control inputs high, then take MR low.
Apply one low going pulse to CPD.
As the first stage (low nibble) contains 0b0000, the pulse on CPD will propagate to /TCD
On the rising edge of the pulse, both counters will therefire decrement to 0xFF.
0xFF is -1 in 2's compliment arithmetic.
The only thing you have to fudge is an overflow flag. If the top bit of the cascaded chain of counters toggles without a /TCU or /TCD pulse out from that counter, your twos compliment count has overflowed.