The UHDM version of Yosys is missing the memory_libmap command:
(base) user@Ondo:~$ yosys -q -p memory_libmap
(base) user@Ondo:~$ uhdm-yosys -q -p memory_libmap
ERROR: No such command: memory_libmap (type 'help' for a command overview)
(base) user@Ondo:~$
Unfortunately, because UHDM is bundled as its own version of Yosys, this makes it impossible to do memory inference while also using SystemVerilog.