The present difficulties are relatively minor ones. Just think about the implications of the picture above. The assumptions of the Wheel of the Year and our calendar systems are a planet with one sun, one moon, seasonal variation, and days which are shorter than years. Where will that leave the Wheel of the Year when pagans leave Earth ?
As a parting thought I'd just like you to ask yourself how you would go about measuring time if you were deprived of all our modern tools and devices ? Imagine that there are no clocks, calendars, or computers. When would your day start ? How would you measure time ? How would you tell the time of year ? Would any of this have been important if the rest of your society were equally in the dark ?
Who knows, you might come up with a better version. Judging by the difficulties detailed in the previous pages that shouldn't be too much of a challenge.
Should it ?