Theoretically, any CAP converter, regardless of the manufacturer, should work with any existing EAS decoder. This should be tested, of course.
There are at least two type approved EAS systems in use that do not interoperate. Specifically, EAS units made by Burk and ones made by Multi Technical Services (MTS) will not talk to each other. Each manufacturer blamed the other and neither would alter their units because they would have to be type-approved again. The situation was never resolved. In our market, there are stations using Burk decoders that had to change their assignments because both primary EAS stations happened to use MTS encoders. Obvioulsy, you wouldn't want that to happen with a CAP converter.