It's very hard to see anything on the surface of Mercury. It is always seen against the glare of the sun. It is always low in the sky, so we see it through a lot of atmospheres, the seeing is worse than it would be for an object higher in the sky. With CCD imaging technology you can see some details, by taking very short exposures and combining them(source). You can't do that with conventional photographic plates.
Lowell produced a map at the start of the century showing supposed linear markings that he thought were the result of cooling.
The best that could be done in the middle of the twentieth century, direct observation images from the Pic du Midi telescope
It wasn't until radar-based observations in the 60s that the rotational period was established. There were some mapping attempts at mapping in the 70s https://www.sciencedirect.com/science/article/pii/0019103572900231 (behind paywall)
It would be hard to identify any features on these drawings with know regions or features on the Mariner images.