Is the wattage important when buying a replacement solder tip?
Does Weller indicate a wattage rating with their tips? I do not think they do.

The heating element has a power rating, this heating element sits in the "iron". For this type of soldering iron, the tip you can replace does not have a heating element. The tip is just a piece of metal (with some coating).

Weller will just indicate if a tip is suitable for your iron. If you want to be guaranteed good operation, get the original Weller tips.

If you want to save a few $$ you can try the replacement tips, even if the wattage doesn't match, it will not damage your iron.

So yes, you can safely ignore the wattage rating, if the tip fits and works that's fine.