Here are ideas from me for names of a few Backgroundponies from different episodes.

Pony 1: She has a Tornado with hearts as Cutie Mark and another name for a Tornado is Twister. So I came to the idea with Twisted Heart or Twisted Love. She is from “Viva Las Pegasus”.

Pony 2: She is usually seen in the Ponyville Spa. Her usual CM is a Palm Tree. Palms reminds me on the sea, beaches and the carribean. So, I came to the idea with Carribean Dream. Edit: Another Idea is “Ocean Dream”.

Pony 3: Yeah, she has a Ferris Wheel as her Cutie Mark. So, I came to both ideas (really simple, I know, but I find both names fits). She is from “Viva Las Pegasus”.

Pony 4: All Nurse Ponys begins with Nurse in their names. Heartstick cames from her Cutie Mark. She is from “Where the Apple Lies”.

Pony 5: I wanted that not all Ponies are named after their Cutie Marks, so I came to the idea with Lavender Sky. She has a violet mane (like Lavender) and is a pegasus (therefore Sky).

Pony 6: A Jackhammer is a typical building machine and I found that this name is good for a road worker.

So, are you ok with the names or do you have other ideas?