My old trainer used to rebrand every import that came into her barn as their European names weren’t always as marketable as she’d liked. Most also had their barn names changed.
My trainer before her had two clients who changed their horses names, and it was a disaster for both. One accidentally changed her horse’s from a classical Greek name to a fun, pithy name that she liked. The grooms didn’t like the name - they warned her against it and that it meant “villain” or “desperado,” not a very becoming name for a ladies’ horse. Sure enough, the horse was a completely trainwreck, developed the dirtiest of stops, and had to go.
Another horse came into the barn for a different owner. They gave her a pretty celestial name, and again the grooms said “no,” is it’s a bad name and means “no go” in Spanish. Well, the mare was diagnosed with significant allergies and had to go back to the seller after months of heartache. The grooms told me - never, never change a name unless you understand the meaning!
Now, regarding name changing in general. This January I bought an incredible horse who was imported. When I finally got his passport, I was able to see his real name, which led me to locate his breeder and former trainer, as well as owner of his grandsire on Facebook. They now follow his progress in the US and are extremely proud of his accomplishments and of their accomplishment as a breeder to have a horse in the US. Without his passport, I would have no idea who my horse was, and would have never been able to track down the people who brought him along. So, if you change a name, always be sure to register the alias with the horse’s USEF details in case a future owner is interested in your horse’s past. My horse was rebranded by the agents when he landed in the US and he’s been fine with his new American barn and registered name, which is nothing like his PZHK name, He knows his American name just fine and doesn’t seem to have any trauma from it. But then again, he also had never been exposed to English so everything was foreign to him and I think he’d also respond to “hey, you!” he’s such a cool customer.