I think the idea that there is a "manga style" that doesn't work if it is influenced by "Western" art, is freighted with so many unspoken assumptions that it would require a thesis to address them, probably titled something pretentious like:
Orientalism In Comics: Selective Viewing Of East Asian Sequential Art Through Western Eyes.I'm not an Art grad, and have no desire to write that thesis, but I think that the idea that there is one "manga-style" is a product of selective publishing/reading. Manga (and
manhua too) are drawn in many styles, aimed at many different markets and age-groups. Many are drawn in the style that Westerners would characterise as "manga-style", but many are much more naturalistic. Western art has been influenced by East Asian art since at least the 19th century, and
mangaka have been influenced by Western comic art since at least 1945.
As regards
the filler-strip to which the OP was presumably referring, insofar as anything "doesn't work", I think it is more likely to involve the fact that Jeph dashed it off for us while he was ill than anything else. There certainly is a sharp contrast between the style in which the girl is drawn and the rest of the characters.
