

Try to write a formula range which covers only lower half of the column which is typical setup in summing numbers( avoiding headers )
You can literally label ranges to use them as variables in Excel formulae, not to mention Excel Tables has more operations and features than you’ll ever need.
limits in columns and records
Unless you are working with an unfiltered, un-aggregated ledger dump straight out of your database (in which case you shouldn’t be let anywhere near an office computer), it’s rather hard to cross 1M+ rows and 16.4k columns in corporate finance.
ever changing formats across versions
The .xlsx format was introduced in 2007 (18 years ago) and hasn’t changed since. Not to mention you can still use all kinds of plaintext formats whenever you want.
I highly doubt that, also, people in corporate finance do not use libraries to process excel files.
=OFFSET(first_cell, 7, COLUMNS(range_name), ROWS(range_name)-9-7)
whererange_name
is the label given to the whole table andfirst_cell
is its first cell.