In your searches did you come across discussions about hoya plants getting too much sun light causing leaf damage?

I am not novice to growing Hoya sp. Too much sunlight can, indeed cause damage to/sunburn their leaves. This does not apply to all Hoya sp., but it does include most. I grow mine indoors, under retrofitted T8 LED lamps, in the late Fall/Winter. In late Spring, when temps are steadily above 55F, at night, they are brought outdoors, protected by shadecloth, in filtered, indirect sun.

I am an active member of Houzz/gardenweb Hoya forum, but we don't really dabble too much into the terminology. Which is what brings me here.

I know how to care for them (what to do/what not to do), I was just searching for a botanical term regarding the splashing seen on leaves, and, if lucky, an answer to why they develop/if there is a scientific benefit.

is that called speckled or mottled? On Davesgarden web site there is an interesting article on variegation- but it doesn't answer your specific questions.