It is
not absolutely clear what you are asking, but looking at your code paints a picture of what you are wanting to do (I think).
You are not properly addressing your table rows in the
.each function call.
To make better use of the JQuery functions, you might be served better to use classes to denote the columns or elements containing your data. That's what JQuery does best. It helps you target id's and classes.
This also helps with code readability and purpose and can be useful if you decide to apply css or if someone else has to read your code (ya... there's that).
If you were to do that, then you can iterate to each row, use the .find() looking for the classes that you are interested in.
It should be modified to look similar to the following where you are iterating through each row, looking for your values by class and assigning them to variables.
Hopefully I got close to the problem that you are trying to solve. Part of the puzzle that my 64 year old brain likes to solve is unraveling intent.
$('#Tbl_Proof_Table_For_Proof tbody tr').each((index, row) => {
let OldField_Name = $(row).find('.old-field-name').val();
let Field_Name = $(row).find('.field-name').val();
var IsDefault = $(row).find('.is-default').prop('checked');
let DefaultValue = $(row).find('.default-value').val();
OldField_Name = Field_Name;
Settings.push({
Old_Field_Name: OldField_Name,
Field_Name: Field_Name,
IsDefault: IsDefault,
DefaultValue: DefaultValue,
});
});