I have (probably as 90 % of world population, that use decimal commas instead of dots as in US) problem with Balsamiq, that you are using commas as value separator. So everytime i am writing some decimal values, i have tu use , instead of ,.
Solution: E.g. in Excel, we are using semicolon instead of commas as function variable separator. And there is simple setting in Excel options - Use system separators (decimal and thousand), with option to overwrite it with a different one. Similary it could work in Balsamiq - if the system decimal separator would be comma, you would use semicolon and give option to overwrite this behaviour. Internaly you would always store it e.g. as comma as today, but on editing of the element you would convert , to ; and vice versa
And even one more relevant improvement - you are always trying to use comma separator, if this is one-line element (e.g. horizontal menu). Why? It would be much easier to edit, if you would use multiline edit with newline as separator, so there would be no problem with commas at all (the problem would still be in e.g. table element, but this could be solved as described above)