When I migrated from pfSense to Untangle - I had a fair number of static DHCP entries that I needed to migrate. So I created this simple Golang utility to convert the exported entries from pfSense into a format that could be imported into Untangle. Note that this code may need to be changed depending on how the Json export from pfSense looks for your particular network.
Here is a link to the repo - which also contains executables for the Mac and for Windows:
https://github.com/srjinatl/pfsense-...le-static-dhcp
Also has a simple Makefile to build either Windows or Mac version.