No, neither host nor guest can change either their review or their star ratings after the reviews are published. The whole point of the blind process system, where neither can see what the other wrote, until what both wrote appears, is so that neither side engages in "retaliatory" behavior, or bases their ratings/review on what the other party wrote in their ratings/review. Clearly, it would not work if for instance, the guest honestly had a great experience at your home, and wrote a review to that effect, but you found the guest very messy and forgetful, and wrote a review to that effect, and then in reading it, the guest wanted to take back their positive review and retaliate for what you had said about them. Or vice versa. So, when writing a review, it pays to really convey what you want to convey, so that you dont' have regrets later on when you see what the other side wrote.
I think it is most decent of people to convey any concerns/ problems they had, privately, rather than for the very first time in a public review. For a guest to never mention to the host that they had a certain problem, until after leaving, then stating it in the public review, seems inappropriate, and would seem more motivated by a desire to punish or shame someone, than to suggest improvements in a way that is effective and likely to be incorporated by that host. I think if you respond to such a review effectively, you can essentially highlight to the future readers of that review, that this is what is occurring: that guest is a person who is not interested in helping the host improve what they are offering, but instead is interested in publicly shaming the host. And to be like that, is not an attractive character trait, and it's also a kind of person that future hosts are likely to decide to decline. Guests who post savage reviews of hosts & their listings have to realize that they will be raising the eyebrows of future hosts they may want to stay with,and may lessen their chances of getting reservations. (Likewise for hosts: reviewing guests with a searingly critical tone wont' endear you to future guests who may not appreciate just what that guest did wrong)
To mention problems for the first time only in a public way, is also inappropriate in that it doesn't give the other side a chance to correct a problem. I tend to only write something critical in a guest review if I have already spoken to the guest about it and that discussion was not fruitful.
Hosts will be unfairly treated by guests from time to time. IN fact I think it's much more likely for hosts to be reviewed unfairly by guests than the reverse. Hosts lack motivation to review guests critically --- though not all hosts are clear thinking and fair minded, in general hosts have little reason to lie or misrepresent what guests were like. But (SOME, not all ) guests come expecting things, may not do their due diligence before booking, may not even read the listing or rules fully before booking ( a problem reported by many hosts) and can thus end up experiencing problems that they themselves have created . THey can expect things they have no right to expect, and then respond irrationally, they can be vindictive, getting upset about not being allowed to do things that the host's rules clearly prohibit, etc. When you are reviewed unfairly, one of the best ways to respond is to respond in a calm, neutral tone, that demonstrates you are the bigger person and the more professional individual.