I have just updated and I am pleased to report that Indigo 7.3.1 is running perfectly on macOS Mojave 10.14.5
Indigo Server running on an iMac (Retina 5K, 27-inch, 2017), 4.2 Ghz Intel Core i7, 48 GB memory.
Indigo Client running on a MacBook Pro (13-inch, 2017, 4 TB3 Ports), 3,5 Ghz Intel Core i7, 16 GB memory.
Just in case anyone wants to know if it works.