Tanabata is a different festival, held usually in July or August. One of the ways you celebrate Tanabata is by writing wishes on slips of paper and tying them to a bamboo tree.
The yukkuris have apparently gotten confused between hanging ornaments on a Christmas tree and tying tanzaku on a Tanabata tree, but the fact that they're drawing the people of the Moriya shrine where you would put something you wished for on a tanzaku comes across as very complimentary.
