Hello I haven't had a lot of time to look at this, but Ill do what I can to help. About needing more entries for holidays, I would try inserting extra rows/blocks rather than tying to move the existing ones. I inserted an extra row by clicking on row 40 and that worked OK. Also, in terms of formatting/formulae it often works better if you insert cells within a block rather than at the edges.
About not being able to find Holiday Rules!K59, this is because Sheet 20 (named "Holiday Rules") has been hidden by the author. This can be changed to visible again in VBE (the Visual Basic Editor). In case you don't know, open this with ALT+F11.