Answer
There's a hard character limit on that trigger-condition definition, and it isn't configurable — the practical fix is to reduce the number of columns/attributes listed there rather than trying to raise the limit. Depending on your use case, either trigger the event on any change at all and move the specific filtering logic into the event action instead, or split a single event with too many watched columns into multiple separate events, each covering a smaller subset of the columns you need to watch.