Our Post Grid Combo plugin will help you query posts by custom taxonomies & terms. This article gives you a clear idea about how to query posts by taxonomies and terms.
Click and expand the Query Post tab.
Now search for “Tax Query” by clicking the Choose button. Now select the tax query.
Expand the tax query and click on the “add” button.
Expand “term” and enter the taxonomy slug on the Taxonomy field, then enter the term IDs (comma separated) on the terms field. Now choose term id from the field dropdown, then select an operator from the operator dropdown.
Now your Post Grid will be updated with the custom taxonomies & terms.