"Love tap" suggest 2 huge buffs
Hum, you should check your dictionary, mate...
Maybe you don't realize that, but even a 25 increase in range is already a huge buff. Tahm got nerfed by 50 shortly after his release, they tried increasing Xin and Trundle range by 25 and finally didn't do it, and when they added 25 range to a number of empowered auto-attacks (e.g. Vi's E), every main was able to tell the difference.
So a 50 range increase is much, MUCH more than a lovetap.
As for the missing health into max health conversion, it's probably something along the lines of a 30 to 100% increase in the damage of her passive. (If she procs her passive on a target at 50%HP, it's a 100% increase, and even on a target with 25%HP it's still a 30% increase.)
Again, an increase of this magnitude is far from a simple lovetap.