Important thing is to keep the pattern of the waveguide similar to the woofers and you can crossover anywhere below frequency the woofer response gets too narrow, and of course higher than the compression driver is capable to.
Just this: I don't think this is correct. There is several goals with pattern width in a two-way, which is coverage angle for itself, sloping of DI through sound power and a smooth transition at crossover frequency. What the latter is must be defined: reference axis, listening window, early reflections, power or DI? Here, the magnitude of increasing sound power due to widening pattern width and the magnitude of sound power reduced through interference cancellations have to be balanced. A perfect matching pattern width at crossover frequency might very well lead to issues due to a lack of energy, that was removed through cancellation.
Thank you for the note on rotational axis. I do not know how to set this, can it be done in observations.txt? Anyway, further investigations will be much more reliable after the next release.