Hi pixie
Okay ... first of all I can't see much wrong with all the spelling variations for RUNDLE.

You say on the other thread, that Emma was "not able to write" ? So obviously she would have relied on others to get "the spelling of her name correct".
Also when you think about how a name sounded when it was spoken (all the speech variations you get with say, people from different parts of England) ... that may have caused the surname to be recorded incorrectly.
OR ... maybe these old records, with their swirly handwriting, have been mis-transcribed at some point ?
The letter "u" and a lower-case "a" for example, are often mistaken.
"SNOOK / SNOOKS" ... an "s" has been added to the end of name. Probably the result - again of old-fashioned handwriting being mis-read .... lots of words were written with a flourish or upstroke at the end .... often it looked like an "s" had been added.
It's likely that Emma didn't deliberately misrepresent her name(s) ... and as these variants are spread over birth, death and marriage records for other family members, then it's quite normal for these "oddities" to occur.
~ Lu