Filename prefix on save image nodes via concatenate node

I have a problem with setting filename prefix. Whatever Image Save node I use (core, or extra nodes), it seems that we cannot pipe the filename by using nodes like the tinyterra node called “3x TXT Loader MultiConcat”.

Especially things like %node_name.widget_name% are written out in the filename and are not “translated” into the node_names and widget values.

I have tried numerous things, to no avail. I wonder if this is a known limitation?

Attached is a screenshot. I’d appreciate any help on this.

Thanks!