No matter what option I select on FMP for the behaviour of the numerical enter key on windows, the key change field instead of doing a end-of-line like the return key.
Why? Can we fix that?
I'm not 100% certain what you're asking, but I can tell you that the Enter key on the numeric keypad won't ever insert a line feed / carriage return. It either commits the record, or moves to the next field, depending on the setting.
About the only way you can change that is to write a script and use a Script Trigger (probably OnObjectKeystroke) to sniff for character 10 (use Char ( 10 ) to check it) and have it do what you want.
Retrieving data ...