Since November, I had gotten two Cherry Mobile Ace (powered by Firefox OS) devices for me and my mom at home. 
Basically, the two Aces function as my secondary phone and as our landline phone unit at home. Being a developer though, I was also interested in using my Ace to test against HTML5 apps that I’ve made.
Prior to the Ace, I already had a ZTE Open Firefox OS device back in 2013. This Ace is a new device, and courtesy of Sir Bob Reyes of Mozilla Philippines, I was able to know how to connect to the Ace on my PC.
Sir Bob’s blog detailed the process how to connect to Firefox’ WebIDE, which replaces the AppManager. It was only weird for me to find that at the end of the article, my own WebIDE wasn’t able to detect the smartphone when it was wired to the PC. Running adb devices on the command line confirmed that problem because there were no devices that it can detect.
I was able to attend the first-ever meetup of Cherry Mobile Ace users in MozillaPH’s headquarters in Makati City last 9th of January. Thank goodness there’s a community you can count on for these problems! I was advised by Mozilla Reps Kim Domanog and Aaron Cajes to try to make use of a Spreadtrum driver from Jan Jongboom’s site. This should hopefully enable my Ace to be detected in WebIDE.
After downloading, I tried to install it on my Windows 7 PC. I ran the DPInst.exe file to install the drivers:
It worked like a charm. My Ace unit was finally detected on both adb devices as well as on WebIDE!
I recall during the meetup Sir Bob’s note that there might be some differences between Macbooks and PCs; there was no need to install such driver in his setup, while I did. There probably is something different with Windows setups because I have already tried following his blog’s instructions on three Windows PCs already to no avail, prior to the Spreadtrum installation above: Two Windows 7 laptops, and another one running Windows 8.1.
Anyway, I hope this helps for those encountering similar problems with their Ace units. Since resolving this issue, I had been able to successfully install and run my own HTML5 apps into my Ace. For all we know, this might not just resolve issues with CM Ace phones, but other similar smartphones powered by Firefox OS as well.