Is it possible to create an excel tooltip with JavaScript that will display the contents within another workbook?

Question

Problem/use case: I work in the audit industry where audit files contain several excel workbooks. Each workbook often has multiple references to other workbooks where the same value exists to indicate to the reviewer that the amount in question across all workbooks agree.

Historically whenever a reference like this exists, the reviewer will open up the new workbook and check that the 2 values are consistent. There are several hundreds of these throughout an audit file.

Question: Is it possible to create a javascript tooltip that displays the values within the other workbooks when you hover over the cell containing the value so the reviewer does not have to manually open each individual workbook?

Any alternative solutions would are welcomed. Thank you in advance!