I want share a LUT I did for my UM4.6K to convert BM film to kinda Alexa Log C.
Test it and let me know what do you think:

Is done side by side with both cameras. Special attention to roll-off, highlights and some color match.
Don't think this gonna get your UM to an Alexa because this not gonna happen. But it helps as starting point.
Use it in the first node to change BM film Log to this Log C, then have fun grading.