LAST() function is not implemented at the moment in order to select the last cell within a range. However, following your example:
=LAST(G2:G9999)
we are able to obtain last cell using the couple of functions INDEX() and COUNT() in this way:
=INDEX(G2:G; COUNT(G2:G))
There is a live example at the spreedsheet where I have found (and solved) the same problem (sheet Orzamentos
, cell I5
). Note that it works perfectly even refering to other sheets within the document.