With the whole "she will usually call multiple times if it's important and she didn't" thing.
Here's the thing, your mother did the EXACT thing we would have told her to do if she were posting here. If she was posting here she would say "When I call my daughter she will not return my call for about a week. This means that if I really need to reach her, I have to call multiple times before she will realize it's important and respond. I don't want to call multiple times just to get a call back, I feel like one message asking her to call me back should be sufficient, what do I do? If I don't call her multiple times, she will miss important messages and events with family".
I'm pretty sure all of us would say, you have no obligation to call multiple times. Leave one message, with all of the information on it. Calling back multiple times only reinforces the idea that it's your job to chase her down, and it isn't. If she misses family events because she won't listen to voicemails, that is on her, not you.
In other words, I think it's completely unfair to say "but my mom changed our dance! She's supposed to call me multiple times if it's important!" Maybe she is tired of that game. Maybe you could just listen to her first voicemail instead of expecting her to keep taking her time to call you multiple times. That's really not her responsibility. Her responsibility ends when she gives you the information, which she did.
Everyone misses or forgets a message sometimes. But that's not even remotely what is happening here. The OP is actually expecting her mother to call multiple times to communicate the relative urgency of her message. That's not really a fair expectation for her to have.