Vinegar may take longer, but is highly effective at removal. Anyway, i don't mean be rude about it, i am just saying don't flutter around the subject. If they do get offended, they could have avoided the offense by taking care of the bird correctly.
I didn't see the update for this, at the least the woman appears receptive. I think it's a good thing what you're doing, just go around with a few toys, proper food every now and then.
"Hey, I got a bunch of extra toys sent this month and I thought they'd suit your Grey more than my bird!" etc. I think that if she maybe see's the thought your putting in to her own bird, that she doesn't really care for, she may be open to letting you take the bird from her (and then you could find a suitable home, etc)
You can take a slightly different approach, and take some toys over saying your bird is bored with them. Same as having a bigger old cage you don't use anymore. Most people don't like being told they are wrong or what to do, and if you do report the bird they will know who did it. WW 3 may start, another option is you could offer to look after it, and the kids can come and visit it. It may no longer be wanted and thought of as a burden. Not everybody will give away or dispose of an unwanted pet.
I pass down my leftover food to a woman I know. She is living out of her car but has a grey named Chester. When I first found out about her situation she was feeding him fries and whatever she would eat. I took the "high road" in talking to her and made little suggestions when the opportunity arose. I asked my breeder if Hahnzels leftover food would be okay to pass down to Chester, and so I keep a leftover gallon ziplock bag and when its full I take it to her. I've also made some toys for him as well.
That's a very very kind thing for you to do goalerjones!!!!! I'm sure that bird is her very best friend in the whole wide world living in her situation. That way at least Chester would be getting some right food for him to eat. Thank you!!!!