True, there might not have been much that could've been done, other than to prepare for the $1875 tax hit. Seems like it's the surprise that was the big deal. Like I said, that's just a matter of being forced to pay some taxes now vs. when you choose to sell.
OP says:
Looking at Hartford's distributions, there were 3 funds that paid more than 20% distributions last year:
https://www.hartfordfunds.com/funds/smide.html
https://www.hartfordfunds.com/funds/grwop.html
https://www.hartfordfunds.com/funds/scpgr.html
All have done well. I'll bet there still is a gain. OP will have to dig out those records at some point to find the basis, might as well do it now and see. Unless they want to set themselves up for yet another surprise and kick themselves again for not knowing about it, when they certainly could and should know. Learn from mistakes and don't let yourself be surprised again. When the funds threw decent distributions in 2017 that should've been another clue to be prepared for 2018.
I've made mistakes and had surprises like this with large distributions. First time for me was in my kid's college fund. It went over the income limit for a youngster (under 14 or something like that) and had to be included in parent's return, which in this case was my ex-, and that was less than pleasant to deal with. Later on VG Primecap was threatening to push me over the ACA subsidy cliff so I took action to take a big CG hit one year and sell it off and preserve the subsidy for the future. There won't be a third time I have to learn from CG distributions experiences.