[wrong answer deleted]
Since you are already using SpritFont+, you need to modify width for some characters in the JSON string.
For example:
{""c2array"":true,""size"":[2,8,1],""data"":[[[10],[11],[12],[19],[21],[22],[23],[34]],[["" ""],[""l""],[""i""],[""j""],[""f""],[""abcegh""],[""dk""],[""m""]]]}
First group [[10],[11],[12],[19],[21],[22],[23],[34]] are character width values.
The second group are corresponding characters. So, for example, to make letter "i" wider, you need to increase the number [12], or move letter "i" to another group (add it to ""f"" for example).