Red hair Fluttershy? It’s a complete palette change whereas blonde would prolly work better. That shade of red would work better on Pinkie.  
Twi’s got a dull skin tone. Then again she got a dull personality, so I guess it works.  
Rarity don’t look like no kind of Pakistani or Korean I ever seen. Lookin more 60s gogo than anything else.  
Dash looks right with that hair color, but the Rainbow on her body is way too subtle. Some dyed tips would make sense or somethin.

That would be awesome.

@RandomFanguy
 
Scottish Pinkie Pie accent
 
Oh… Oh gawd

So the one with a light mane colour is a redhead, and the one with a colourful mane is an albino?

Hmm, I wonder if those come with accents.

Time for you to block the tag.
 
Anywho, the artist has a lengthy description of her headcanons but the breakdown is:
 
Fluttershy is a 14 year old French girl named “Fleur Samons”.  
Applejack is a 15 year old American kid named “Alex Johnson”  
Pinkie is a Scottish girl, age 13, named “Paisley Park”.  
Twilight and Spike are 15 and 10 respectively, they’re from South America and Twi’s name is “Tiaret Silvia”.  
Rarity is from either Northern Pakistan or South Korean (both?) and named “Rachana Song”; she’s 14.  
Dash is fourteen, German, and named “Romy Drescher”.

Huh. You know being near platinum blonde would make sense for Dash.
 
Lighter the hair, easier it is to dye.

Eww natural hair colors!