First, let me concur that Darktable is not great. I found it to be neither quite as simple as Lightroom, nor as powerful as RawTherapee, and severely lacking in documentation.
> Another dealt with trying to set color temperature. There are two places color temperature can be set and they'll both conflict with each other.
There are at least three colour temperature / white balance controls in RT; more if you count output colour space primaries, Lab space curve, etc. as ways of creative white balance control.
I’m not sure I see any particular conflict between them. They all do different things; some of them are more relevant if you want to achieve the most precise representation (e.g., you are digitizing analog prints or paintings), others are more relevant if you are going for a creative look of your own.
It’s probably best to consult RawPedia[0], but as far as I understand:
— One of them controls raw data interpretation, and affects how different tools work down the line (e.g., highlight recovery or targeting sky with wavelets). As far as I understand, you probably want to keep this one technically correct and as close as possible to the true neutral white/grey point; at this step you are helping the tool do the rest of its job and not trying to achieve a look. If you use a colour card, a DCP profile, etc., then you know exactly what to set White Balance controls to.
— There are a couple of controls under CAM model, which you may or may not be using depending on your profile. With scene illuminant you set… well, scene illuminant (the light you have in your scene), and viewing conditions allow you to shift colours to make it look right if you know your photo will be viewed in an environment with particular light.
— Then, of course, you have dozens of different ways of creatively controlling perceived white balance via different curves or CLUT; I think these are most handy if you are going for a look.
[0] https://rawpedia.rawtherapee.com/White_Balance