Also to clarify, that "-SUM(Acc_T171)" and similar formula syntax is coming from the converted specification and would never be necessary when editing or creating financial statements with Adagio.

To add cell values together, you can do any of the following:

=e93+e94 (to add two cells together)
=sum(e93..e97) (to add a range of cells in a column)
=sum(e93..j93) (to add a range of cells in a row)
=sum(e93, e97, e102) (to add specific cells together)

If you are still having problems, post here what cells you are wanting to add together and the formula you are using to try and create the sum.