I haven't kept cherry barbs in years so I can't say for sure, but I'd go with your gut first of all. Even if everyone were to tell you it was a good idea, if you are personally not comfortable it'll bug you in the long run. Me, I'd be fine with your numbers from a biological standpoint but am not familiar enough with their activity to comment on footprint.
As for white clouds, I have always liked them. I currently have a group of 13 with some assorted snails in a planted 10 gallon. I have kept them in a number of tanks over the years. Some large and some small. What I can say is that the never act right, for me, in groups of less than 8. That is to say they are timid in smaller groups. In larger groups they don't always stick close together, but they are out and about more. Weaving in and out of leaves and feeding from all levels. Rather than hiding behind the plants or hardscape coming out only to eat. I have never had any issue with them nipping at the snails etc either.
As someone who had tried and failed a number of times to get a planted tank going, I totally understand not wanting to tear it down and start again!
As an aside, ember tetras would look good in your 10 gallon too and they are easy to find.