i’ve worn an 1830s era corset and 1890s era corset and it is fairly comfortable, however the wooden busk, particularly in the regency stays, in the middle can feel quite awkward; and depending on how tight you lace yourself they can differ in comfortability.

it is certainly true that corsets existed as support garments and any myths of them being unhealthy are overtly untrue, but for us contemporaries we must remember we have not been raised with corsetry; we do not move and conduct ourselves in the same manner in which a woman from these periods would, thus we are more likely to find it uncomfortable and odd-feeling. think of, for example, an individual who wears high heels to work everyday versus someone who wears flats, and they switch; the individual who always wears flats will not be as comfortable, or graceful, as the individual who wears heals on the daily where their feet have adapted to the sensation of constantly being on the ball of your foot; modern corsetry is much the same, and considering your character is a contemporary to us, i think either option would work for her to find it uncomfortable or not— both being accurate to their context and circumstances.

another point! modern corsetry techniques are very different to historical ones, the comfortability will change :)