Hello
I am a Level 20 Top Rated Freelancer on the Freelancer site and I have over 29 years extensive experience with Filemaker Pro (including v12) and have developed, deployed and maintained many instances from very large and complex down through to small more simple deployments.
I also have some clients who were in a similar situation to you, where their developer is no longer available, requiring reverse engineering and updating the previous developers work, to the currently active database solution.
If you would like to send through some additional information on your project and desired outcomes/developments, along with a copy (sanitized/cloned if required) of your current database, I can review the details and structures to better understand the requirements and get back to you with any queries. We can then confirm a plan and I can provide a more accurate timeline for completion.
*Note that I am Australian, so language barrier will not be a problem and I usually set up a localised development environment for each client to developing/test changes prior to merging into a live database, so timezones will not be an issue either.
Thank you
Darren