Why not just write a PowerShell script to automate the Office app to do the conversion for you? Seems like you could have an "input" folder where you drop the PDFs. Run a Powershell script (could be scheduled to run periodically) that takes any PDFs in the folder, converts them using Office and drops them into a "working" folder that your team can then edit. Once the editing is done have the team put the files into a "ready" folder that another Powershell script (also schedulable) reads from to convert to HTML. Have that script convert the files and place them into a "done" folder.
Here's a starter link for working Word in Powershell.
There are also third party products that can do these types of conversions as well but you have to buy them. Not sure if that is an option for you or not.