I'm changing my answer to mild.

I only have the Red to compare it to directly, which itself is a touch less bitter than Campari (more subtle, softer, more complex spice flavors). But the Lyre is less bitter than the Red, also sweeter, and it has just a touch of citrus acidity (which I don't recall from any alcoholic Campari type liquor). The Lyre is generally a little weak though it does give the general impression of the right sort of flavor.

Though it occurs to me I'm tasting the Red at a warm room temp, and the Lyre cold (it says to refrigerate or use within 2 weeks... No alcohol to preserve it!) I'll leave some out and confirm again later. ... Nope, controlling for temperature doesn't change my assessment.