Firstly, thanks to Phil for stepping in with a solution so quickly and it seems that what you've done is fine.
The reason for the change is because certain types of database table structure have a limit to the size of a row and the orders table was approaching that. So columns like the IP Address which used a default max of 255 characters were reduced to reduce this row size and was set to something in this case which should allow for even the longer IPv6 addresses. For some reason in your orders table there is a slightly longer value which caused the change to fail. I've made a change so this won't cause a problem in the future and what Phil has done for your site, Trendyhounds, is fine and you won't have any problems.