"The results by Smith (2004) as well as those reported in this paper do not pertain to the situation in which the variables develop sequentially, but to what is called the non-sequantial development of variables."
Hi there. Is this sentence more or less logical and correct?
1. "The results by Smith" is understandable, but not technically correct. I would insert a verbal, obtained or published, after "results".
2. As you suspected, the verb structure is problematic. The sentence has "do not pertain to...but to".... This would be better as "pertain not to...but to". One could argue that a second "pertain" is understood after "but", but the rephrasing is better, IMO.