When you are trying to perform this replace, this won’t get replaced with the Datarow object CurrentRow instead it will be replaced with the String "CurrentRow".
It will not be an Expression and it will be just a String.
Better approach would be to convert your formulas suitable for either a DataColumn Expression and update the datatable or as a Excel formula itself where you use Write Cell Activity inside an Excel Application Scope and then maybe use Autofill Range Activity to apply the formula to all other cells.
Excel Formula is preferred as it seems the Formula would be a bit more complicated (multiple if’s)
Let us know your thoughts on this and if needed further help on the conversion.