Many sound editors do not comply with this requirement, and set the creator type to their application type. A work-around for this is to save your sounds directly into a sound suitcase. It is a good idea to let the makers of your sound editing software know about this problem. Some keyboards can only accept 2 keys down at once, most can handle 4, and many keyboards can read more than that, but sometimes in an unpredictable way. On the Macintosh, a good way to test your keyboard is to open the Key Caps desk accessory from the Apple menu and try pressing as many keys as you can.
Some keyboards also have different key response sensitivity.
This response time is the product of many factors, from the drivers that handle communications between the keyboard and the computer to the mechanics of the key switches themselves. The best thing to do is try out different keyboards and test their responsiveness. We have no idea why this happens. Because of this, you need to have enough free RAM to cover the size of the sounds you are loading in. On the Macintosh, allocate as much memory to BackToBasics as the size of your sound suitcase, plus 500K for BackToBasics to use.