The simple fact is that 3CX does not support their own Call Flow Designer with their 3CX hosted service. So I think it is safe to assume they will not support 3rd-party tools in the near future.
At VoIPTools, we are building custom wallboards pretty much continuously because everyone wants something different. I cannot speak for 3CX, but I think it is unlikely, given what we are being asked to do on a daily basis, that 3CX will choose to build a large number of varied or customizable wallboards. 3CX has offered the same single wallboard for more than a decade.
The 3CX hosted service is intended for small-to-modest size 3CX implementations. Their service (today) may not be the best fit for very large implementations, or for customers that need Call Flow Designer applications, or 3rd-party solutions. But we need to keep in mind that 3CX is providing a very cost-effective hosted solution. To do so, they need to build a business model that is highly scalable (minimizes staffing requirements) and that means they need to focus on relatively generic implementations of 3CX.
It could be argued that the 3CX Partner community exists, in part, to implement and support the more complex implementations of 3CX -- those that do not easily fit into the low-cost generic implementation model that is the sweet-spot of the 3CX hosted platform. For those customers that have more complex needs, 3CX can be hosted with providers that do permit the use of the Call Flow Designer and custom wallboards (3rd-party tools).
Today, it is not uncommon for 3CX to be hosted in many different environments -- on-prem or hosted, at 3CX, AWS, Azure, or Google, and installed on both Window and Linux. As a 3CX Partner, your job is to implement 3CX in the environment that works best for your customer. You can argue that standardizing on a single platform (like 3CX hosted) works best for you. Fine. But there is a reason why 3CX is found is so many different environments -- because one size does not fit all, and it never will.
