I really thought that after everything that happened with Lyra we were done with this, but no, it seems that will still don't know how to compromise and are not aware of our own freedom as fanon writers. I really thought the brony fandom had a new found maturity by now, as many of the few things I don't like about the fandom (which are outwayed by all the things I do like about the fandom - in fact there's only three (with a possible fourth) things I don't like about this awesome fandom). Unfortunately after seeing the name change of yet another pony (ironically a pony that Lyra is often friendshipped with.) I find that we still don't get it, do we?
First of all, while there are plenty of fanon names I like better than toy names we don't own the show itself, and Hasbro do have the freedom to name the ponies what they like in the toyline. I will admit, I was sad to see that the name Bon Bon would not be used for the toyline (mostly because I've taken to like the "real" Bon Bon who she was named after), but I am not going to complain about it, becuase there is no reason to. These ponies names are never used on screen and probably never will be. Since Bon Bon/Sweetie Drops is the latest to be changed, I will begin by using her. Is there actually anything stopping you from still using the name Bon Bon in your fanart and fanfictions?
The same applies to the other multiple named ponies; I was one of the first bronies to use both the fan name "Lyra" and the toyname "Heartstrings" as one name (though I do not in any way claim to have come up with the name) because I actually liked both names equally, and "Lyra Heartstrings" really did work beutifully as a full name in my eyes (it is the only time it did, in my opinion). I honestly couldn't believe how much time and effort among bronies was dedicated to creating protest art demanding that "Heartstrings" be changed back to "Lyra" when it could have easily been spent simply creating fanart and fanfictions starring Lyra, if she's that important to you. No one would have jumped on you for still using the name Lyra, even though her toyline name was Heartstrings. Eventually Hasbro compromised, and rereleased her as "Lyra Heartstrings", but at the end of the day, they really shouldn't have had to.
What staggers me the most, is that long before all this happened, there was already a background pony with two names; Derpy Hooves/Ditzy Doo. Back then, many bronies would compromise by either choosing a name and sticking to it, or giving her both names at once (usually one name being her real name, the other a nickname) and nobrony would argue about it, at all. All of a sudden, we seem to be more prone to arguing about it. A YouTube Series staring Dr Whooves (or should that be Time Turner?) was placed under brony-controversy for openly refering to Derpy as "Ditzy Doo", despite the fact, that in a planned later episode they were going to use the name "Derpy" as well. Last time I checked, the creator of the series was on strike, due to all the hateful comments about the character's name. I really thought bronies were better than this...
Like I say, there are some background pony names where I like the brony name for them better, and there are some where I like the toy name better, and some that I like equally, so in which case I will think of a compromise. I have a fan series planned, and if at anytime it calls upon background ponies - they will be named accordingly to my own prefference. I would advise that you simply do the same, other than complaining on the pony's page that she should be called something else. There are ways you can compromise and use both names at once for example make it a full name like "Lyra Heartstrings", keep one name as the ponies real name, and use the other elsewhere - like as a nickname or something else. A good example (other than Derpy/Ditzy) is Vynyl Scratch/DJ PON3; I can't honestly be the only one who sees that the latter of those sounds more like a stage name than an actual name - the compromise has been staring you in the face the whole time. As for Bon Bon/Sweetie Drops, in my fan series she will be 100% refered to as Bon Bon - too many deliberate "coincidences" for her to be called anything else, but that is my fan series. Any fan material of your own she, and every other pony, can be refered to as you like. There is no point in complaining about it in the pony's talk page.