Suggestions

Handle Different Locale

Include the option to handle different locale

Office.context.displayLanguage 

SPELLNUMBER

Include some additional parameters for language and currency
A few examples if cell A1 contains the value 142.23
=ASAPSPELLNUMBER(A1,"EN", TRUE, "Dollar", "Dollars", , "Cent", "Cents") returns One Hundred Forty Two Dollars and Twenty Three Cents
=ASAPSPELLNUMBER(A1,"EN", FALSE,,,"Comma") returns One Hundred Forty Two Comma Twenty Three
=ASAPSPELLNUMBER(A1,"NL") returns eenhonderdtweeenveertig komma drieentwintig
language = Optional, text string representing in which language the number is spelled out: English = EN or omitted, Dutch = NL, German = DE.
currency = Optional, logical value: to spell the number as a currency = TRUE; to spell the number just as a number = FALSE or omitted. For example spell the number 2 as "two dollars and no cents" or just "two".
cur_singular = An optional text string for the currency spelled singular. For example "dollar".
cur_plural = An optional text string for the currency spelled plural. For example "dollars".
comma = An optional text string for the decimal separator used. For example the comma sign (",") or point (".") or the word "comma". If omitted then it will be automatically filled depending on the given language: English = "comma", Dutch and German = "komma".
cur_cent_singular = An optional text string for the word used with currency for the amount behind the comma, singular. For example "cent".
cur_cent_plural = An optional text string for the word used with currency for the amount behind the comma, plural. For example "cents".

New Function - BUSDAYNEXT

The equivalent VBA function is BUSDAYNEXT

New Function - WEEKNUMBER

The equivalent VBA function is WEEKNUMBER

New Function - CONCATVISIBLE

New Function - PERCENT OF

PERCENTOF(number)