FWIW, I've worn a pair of shell cordovan Rancourt boots out in some really shitty weather (New York in winter) and always managed to work out any damage, even water marks like the ones above. That being said, it does take a fair amount shoe care product and elbow grease to get them looking pretty again. All shell cordovan changes color with age and wear.
My Rancourt boots are color 8 and actually look better after getting beat to shit than they did new. It is likely harder with lighter color shells which darkens with abrasion and age. Most people like whiskey to look..well..whiskey.. and not mid-brown which is what lighter color shells age towards. So pairs of whiskey shell tend to get babied more to keep them lighter.
I was in on the C&J whiskey Skye 2's GMTO and I'll likely not wear those in wet weather because they have a leather sole and I value my life when crossing over frozen pavement. However, I don't baby my shell cordovan shoes like a lot of SFers advise and mine are fine. Shell is really far more forgiving than people give it credit for and with the right care afterwards you shouldn't fear getting stuck in the rain.