Formula/method to link the data/responses I get from my forms into a different table.

so the problem is that "Responses[When was this transaction made?]" refers to that entire column of that table and therefor that IF statement is trying to output an array of results.  It appears that formula is in a table of its own and array output are not allowed in a table.

if the tables line up the simpliest answer may be to add the @ symbol to tell excel to use the corresponding row of the array/table:

Responses[@[When was this transaction made?]]

That said the better way is to either expand on the response table and make your calculations there or just pull the whole table and perform whatevere filter/calculations you need and spill the whole table/set of data all at once.