Is Soraka's passive good enough? Here's my idea of what it could look like

Sometimes I feel like her passive is actually useful around 80% of the time.
These include when I'm trying to run away from the enemy and an ally is ahead of me, or when the teammate actually survives being below 40% of health.
It doesn't function around walls so it's kind of frustrating feeling like you don't have a passive, and usually at least in my experience, teammates outright die too fast for it to matter if I'm trying to get to them in time (Especially with mobility boots), so I end up asking myself a lot "What is the point of this useless thing?" It's actually quite frustrating.
Normally I have to deal redemption AND my ult and maybe they'll survive long enough for me to get there, if its a 1v1 scenario, but seeing how grievous wounds is thrown around its kind of rare
Here's a suggestion I was thinking about:
Stars used to guide soraka in her lore, correct? I was thinking if stars could start appearing between you and an ally that's low health and these stars are gatherable just like bards chimes. Each one you collect gives you 10% MS (For x seconds) stacking up to 100% as well as 1% more healing upon your next W on that lower health target, stacking up to 20% . You lose all of these stacks once you are struck or once you use your W on that low health ally. This passive would activate at a longer range, and the spawn rate of stars would depend of how much damage the ally champion is taking consistently.
Edit:
"and the spawn rate of stars would depend of how much damage the ally champion is taking consistently."
What do I mean by this?
It's supposed to proc in a similar fashion as steraks gauge would, in that it expresses urgency.
-If your adc gets Q'd by varus and their health drops to 50% from that one Q, more stars will proc between you and that ally.
-If poppy is getting wetnoodeled by the entire enemy team, and they are down 50% to begin with, then not many stars will proc between you and that ally (But there will be still, since they are receiving some damage).
The idea for this was to sacrifice the "reliability" of a constant 70% MS for a bit more utility and functionality with her kit+lore.