1. There have been about 20 employees working in the overseas marketing division remove the CURRENTLY 2.He asked whether/if the company's guidelines on personnel expense accounts had shifted replace HAVE with HAD

The adverb "currently" conflicts with the present perfect tense.

There have been about 20 employees working in the overseas marketing division in the past ten years. Or "There are 20 employees currently working in the overseas division". He asked IF the company's guidelines on personnel expense accounts have shifted or "He asked that the company's guidelines on personnel expenses be shifted. (He asked them to consider shifting the company's guidelines). One of these are correct, depending on what is meant.

"There have been about 20 employees currently working in the overseas marketing division." You could say for example either: "There have been about 20 employees resently working in the overseas marketing division." or "There are about 20 employees currently working in the overseas marketing division."

There ARE about 20 employees currently working in the overseas marketing division.