I have seen many people in United Nations have had trouble with being able to type quickly enough for training while using their phone or tablet and still want to participate in the top recruiters competition - http://habboun.com/utilities/top-recs - which is another good way to rank up quickly.
If you cannot find a laptop/computer to train on, here are a few tips to improve training from these devices:
1. If you want to train often, try making a script for yourself, you are free to change whatever you want to suit your needs. The script in the trainer guide is just a guide, the bare minimum.
2. If possible, print out the training script that you are used to using and have it handy. This can help with your hand-eye coordination for training, improve the efficiency, and makes you more prepared.
3. Try using shorter sentences than what you're used to. Of course, don't let it be just a few words, but have your script personalized enough to where you can get the needed information across by splitting up the lines into shorter sentences.
4. Practice, practice, practice! You can make a Habbo room the size of the United Nations training rooms. And guess what, they are free.
Take advantage of that for practicing your script on mobile or tablet. Do it frequently enough, possibly once a day, to help with your comfort level of using the app.
5. It's possible that you may have a few errors every so often if you're not used to training from the app. Don't let it discourage you! Pick yourself up and move on, improvement can only be made!