Sometimes when adding decimal values to a variable, extra ghost values will be added out of nowhere, but as very small amounts (which makes the problem more annoying in some ways). For example, the variable value starts at 1, and 0.1 is added to it, but when the variable is displayed, it shows something similar to 1.10000000000001, and that extra 1 increases with nearly every 0.1 added.
The only real impact this has is with displaying the variable as text for a user, as they will see a bunch of extra zero's that mean nothing taking up a lot of space. Also, you can solve this problem by multiplying a variable by 10, adding 1, and then dividing it by 10 (apparently this doesn't always work, and those extra decimals occasionally sneak through), but that turns what should be one trigger action into three.
The other variable-related issue is with names. I'm not even sure if this could be considered a bug, but basically if a variable contains the name of another variable, parameters with the larger variable will sometimes get confused as to which variable is being used, and instead place the smaller variable's value while surrounded by the remaining string of the larger variable's name