The same in DaVinci...

Any help?

Something goes wrong in the way the color matrix is written in exif.

If you use no color matrix (with Rawtherapee choose "no profile" at color management) and then you copy the color matrix 1 coefficients (multiplied by 100 so 1.89 becomes 189..) in RT's "channel mixer" you take the colors you describe as "perfect".

In case you have difficulty finding those multipiers here they are .. as written in exif

1.80477 -0.54011 -0.26466 -0.19744 1.36156 -0.16413 0.21195 -0.83605 1.6241

and after X100 .... 180 -54 -26 -20 136 -16 21 -84 163.

We have to dig in DNG specs to find the correct writing of color matrices and correct it in exif data..

Edit. Looks like the multipliers are at the inverse order .. 163 -84 21 -16 136 -20 -26 -54 180.