A few things worth noting are:
CR2 is a stills format, and therefore is specifically encoded for a display referred pipeline. In Resolve it is treated in a similar way to Adobe Camera Raw, and you’ll notice if you enable Highlight Recovery that the white point shifts down to accomomodate extra highlight detail so that the signal never goes above 1.0. There are other limitations too, such as non-access to Resolve Colour Management. Therefore you should convert your CR2 files to CinemaDNG before proceeding further.
Now, although the previously inherent display referred limitations are lifted (RCM works and and highlight recovery allows values over 1.0), there still is the paradox of CinemaDNG to contend with. CinemaDNG is still based on Adobe’s display referred intended stills format, in that it maps the full signal into the 0.0 to 1.0 range i.e. sensor saturation is mapped to 1.0 as opposed to the scene referred approach where reference white (90% scene reflectance) is mapped to 1.0. Now, unless 5D raw reaches sensor saturation around 2.2 stops above middle grey (18%) it would appear that some signal scaling is occuring, so perhaps it’s worth looking into reversing that scaling in order to attain the actual scene referred values, and from there (with the signal in linear light) it should be a simple matter of a 3x3 matrix to convert to ACES primaries.