When using find & replace (note: only when actually replacing), everything is switched to use expression. That may lead to error messages and crashes when there is no expression alternative. Also, in some cases in the wizard the description field and the field where the object icons are shown are replaced by gradient grey rectangles, when manually switching between default and expresion.
Examples (before = original, after = after changing something using "Find & Replace"):
System.Compare
before: Value1 equal to Value2
after: Value1 0 Value2
S plugin
Add/Overwrite in Array
before: insert Number 1 to {"some array"} at "end"
after: 0 Number 1 to {"some array"} at "end"