after some initial testing, we have found some formulae related issues.
1) first is about "shared" formulae formulae" (ie the ones obtained by dragging one formula over adjacent cells).
I'll attach you two simple xlsx file, both work exactly the same in MS
Excel, but one doesn't work fine in Spreadsheet component.
Compare the first section of the two files: the row tagged as "Cumulative" doesn't work in Spreadsheet in the second version, since the "shared" sum formula doesn't work.
NOTE: the first version is produced with MS Excel, the other with a famous third party commercial XLS library.
2) empty cells are not considered as "0", and give an error when used as parameters in formulae (see second section of any of the attached file, compared to first section) the yellow empty cell gives an error
3) SUMPRODUCT doesn't work. It's sufficient to test it on one of your online examples to verify. It throws an error
thanks and regards,