For labels the ObjectDetect module might work very well:
You just need to put pictures of the labels you want to recognize in the module's directory (see the doc at the link above), and they will be processed when the module starts up. We have done this successfully with, e.g., getting a logo like Priority Mail (shown in the module's doc) from the web (google images), saving the picture to that folder on the microSD, and then we can recognize it with ObjectDetect.
It would usually make sense to try to save the picture at a resolution that roughly matches what it will be when captured by JeVois (e.g., do not save a super high-res picture of the label if you will run JeVois at 320x240). Best results would actually likely be with first pointing JeVois to the label you want, making a screen capture, cropping that around the label, and then saving that crop to the microSD folder. This will maximize your chances that next time you see that same label with that same camera they will match.