I believe the "splash" only refers to the white or cream colored areas on the leaf. Some have more the others and people have coined the name splash to donate the difference. Hope this helps.

Probably better to ask in one of the Facebook hoya groups that have more participation. I do know there is a Hoya carnosa "Freckles".

http://www.myhoyas.com/C/carnosa/Freckles/eng.htm

I am not sure though if there really is a Hoya carnosa Freckles Splash or if someone just decided to add "splash" to make it more alluring to buyers. I have noticed that sellers are adding the word "splash" to anything and everything now.

Splash can happen on any hoya. Here's a very splashy hoya carnosa leaf but this is just a regular old carnosa. Oh sure, someone could market it as "splash" but that would be insincere.

https://www.gardenweb.com/discussions/6034380/for-the-love-of-all-leaves-splashy#n=13

I guess I have become leery of the term "splash" now. I'm not saying there is or is not a Freckles splash but I would take it with a grain of salt.