There are issues off ill repair, and there are issues of challenging terrain that just cannot be conquered with smooth, gradual slopes on sidewalks--two rather different things.
Just as a general comment, I'd say the less affluent of the former Iron Curtain countries (Bulgaria, Romania, Ukraine--probably also Serbia, Bosnia-Hercegovina, Kosovo and North Macedonia, though I've seen little or nothing of them) are more likely to have troublesome city sidewalks.
Within other countries, more touristy (typically more affluent) cities may have more money to spend on things like sidewalk maintenance. So places you've heard of may be less problematic than off-the-beaten-path places.
Then you have terrain issues. Steep towns with cobbles to walk on (medieval centers sometimes have no sidewalks, so you're walking in the cobbled street) can be really troublesome even for folks with normal vision, especially on wet days. Two I can remember struggling with were St-Emilion in southwestern France and Plovdiv, Bulgaria. Similarly, towns built on hillsides with stepped lanes rather than streets are a challenge: one such example is Taormina in Sicily, but I think I encountered that sort of thing in some small Greek towns as well. Even in less extreme situations you sometimes run into sloping sidewalks with some shallow steps showing up every 3 to 6 feet or so.
Would Venice be a problem with its hump-backed bridges?
And would sheer hilliness be an issue even if pavements are lacking steps and are well-maintained? Larger hilly cities like Rome (maybe Lisbon, but that trip was a long time ago) could perhaps be managed with heavier-than-usual use of buses. Buses will not usually be a viable option in a place called a "hill town", so great caution should be exercised in choosing to visit such places.
It might be easier for the forum to help you if you proposed places you were interested in (at least regions if not individual cities and towns) and we could react to them. I really think there are tons of places that would be manageable.
Silly comment from someone whose horrible native vision is reasonably well-corrected but who has extremely poor balance: Not rushing is key. I have fallen flat on my face in Budapest and Leon, and flat on my back in Berlin. I've wandered around with grotesquely-bent eyeglasses (until a kind optician fixed them for me) and a black eye. All because I tend to hurry so I can see more.