Rolling Magma Totem Targeting Range (Projectile Speed)

When using slower projectiles and reducing the speed of rolling magma for use with totems, the totem's targeting range seems to adjust to the inside edge of the AoE of the first impact of rolling magma - essentially needing enemies to be inside the totem with enough reduced projectile speed.

This seems like intentional design for projectile skills with totems (?), but seems completely antithetical for rolling magma as rolling magma's effective range is much larger given the skill's ability to chain much farther than first impact.