$ cat mhf_1697445335_20231016_run_transitions.dat
event name: [Run transitions], time [1697445335]
tag: tag: /DWORD 1 4 /timestamp
tag: tag: UINT32 1 4 State
tag: tag: UINT32 1 4 Run number
record size: 12, data offset: 1024
...

data is in fixed-length record format. from the file header, you read "record size" is 12 and data starts at offset 1024.

the 12 bytes of the data record are described by the tags:
4 bytes of timestamp (DWORD, unix time)
4 bytes of State (UINT32)
4 bytes of "Run number" (UINT32)

endianess is "local endian", which means "little endian" as we have no big-endian hardware anymore to test endian conversions.

file format is designed for reading using read() or mmap().

and you are right mhdump, does not work on these files, I guess I can write another utility that does what I just described and spews the numbers to stdout.

K.O.