Does jean Lily alter santa lancer 's noble phantasm heal?

Yes it heals, it is just 1 turn long.

Probably somewhere in London, lot of homunculus enemies in that singularity.

Her Noble Phantasm >>DOES NOT HEAL<<. Rather, it increases the >>HEAL RATE<< your party receive for 1 turn.

This site has servant wiki with all the information listed; go through them up top in the "Servant" tab if you desire.

Homunculus Baby drop rate highest is at Southwart in London chapter. Average 52.9ap per drop with a drop rate of 35.9% which is pretty solid.

Here's the drop chart that's been updating and ran by some very cool folks and a group of data collectors, with data on both JP and NA.

https://docs.google.com/spreadsheets/d/1_SlTjrVRTgHgfS7sRqx4CeJMqlz687HdSlYqiW-JvQA/edit?usp=sharing

The point of her NP is to boost everything that comes after it. Usually this means damage but it can boost healing NPs like Meadea/Saber Lily and Irisveil. It also helps a little to get debuffs to stick on enemies that have resistance.

None of these 1-turn buffs are particularly big but it does help a bit with everything.