It's probably why you added it, but that green tea should be a great addition for the tannic acid alone. Especially if you steep it a long time before adding it, you can get quite a bit of acidity from the tea. You always need to add acidity to mead.
I imagine that's why you added the lemon to the blueberry. Some buddies made a blueberry mead many many years ago that was AWESOME. Like a light red wine.
My best was a kiwi mead. Second bests were sparkling ginger mead, and pineapple, which I have a couple bottles of still...they're about 11 years old now
Please keep us posted on your meads. Quality mead is good stuff.
Janx