At least one thought to the contrary (though I don't think you're wrong to look at it that way) our bodies cary the record of our emotional wellbeing, even if our memory doesn't

This was probably quite good for their mother, both psychologically and physiologically, even if she will have no memory of it.

I'm sending love, I can't imagine how hard it is to navigate watching someone fade away like that 🫂

The thing is, some of the delusions are deeper rooted, and are likely to recur more, in one form or another. Even if mom doesn't "remember" she's getting married, and the event doesn't link with that underlying cause, she'll have a happy day, and, if she asks for a bridal shower again, they can show her pictures and mementos of the day.

Whether it's right or wrong, I feel those who "share" their "compassionate" acts on social media is just plain weird and offensive to the critical mind. True benevolent compassion does not dwell in boastfulness.

When the time comes is going along with it the right thing to do?

One thing to note is that, as far as I know, dementia is not a normal symptom of aging, so your parents and you might not have to go through it, especially if you don't have a family history of dementia.

I don't think this is the right thing to do according to psychologists. I've heard you're supposed to avoid outright contradicting their reality, while also not going along with it - often by distracting them for a bit so they'll forget what they were on about.

When I worked in memory care I found that the easiest way was to play along. I had co-workers that did their training decades before I did and they were largely attached to "reorientation in time", which is a nice way of saying confronting their delusions, and it was just upsetting for everyone.

I don't want to tell Doris her husband isn't actually late coming back from the shops, or that her parents aren't coming to pick her up, or that she doesnt need to pick up her small children from school. Wouldn't you get upset if some random stranger insisted that your spouse, who you remember waking up next to that day, died ten years ago? Or if that random 50 year old stranger insisted that they were actually your small child that you definitely dropped off at school that morning?

Unfortunately humans aren't capable of experiencing objective reality. Instead everything gets filtered through our brains, which even in a totally healthy state still can't help but filter reality through a layer of subjectivity. Personally I'd pick being lied to every day over being told my life has already passed me by every day.

Do it again. Because why not? It makes her happy.
And if you want a cynical comment: you can always re-gift the same things again.