table summaries label

Is there a configuration or custom development way to change a column summary label from let’s say SUM to Total?

Not sure if this is the best way, but it was quick.  You can use css:

.nx-summary .type{

.nx-summary .nx-fieldtext:after{
    content: “(Total)”;
    text-transform: none;

If you have more than one summary, you would need to be more specific in the css, however.