I mean, Viscount isn't exactly high nobility. Between Baron and Count. The early English version was not hereditary; I thought it and baronet were made specifically to be sold off, but I might be wrong about viscount.
"High" in the sense of "not the lesser nobility" like a Baronetess, knight, or any other sort of petty noble would be. A Viscount is a Peer, and traditionally is subordinate to and has the ear of at least a Count if not higher. It's a rank that carries adminstrative and judicial responsibility as adjunct to a county often in addition to responsibility for a municipality within the fief.
That's simplifying greatly, I admit -- this stuff is legit complicated and depends a lot on time and location -- but the historical record is consistent enough for me to say this should actually be a big deal, especially for the relatively small scale of her contribution.
Plus this is probably a translation of a Chinese noble rank.
That's hard to say. Like yeah, it's a Chinese comic by origin, but Chinese people are just as capable of reading about European systems as you or me. The trappings of the story are clearly European, and I don't recall seeing any of the usual Very Chinese Culture Stuff (like being super conscious of face and such) so I'm going to treat it the way it's translated until proven otherwise.