Really thank you for the great post, sadly it came in a time when I was forced to a stop an overlooked it, I'll implement the bug fix and find a way to get the suggestions in!
I'm working on it, fixed the frames, thanks a lot!
As for the spaces, sadly the RMMZ header won't let me add " hours" or " and " but it trims the spaces, so you have to add them manually but it's doable. I don't use auto space because a dev might want to write it as 27h:30m
About the "Out of range value" are you talking about variables? Because there is already a "return 0" option as error handling, if it's about a switch, I didn't add an error handling as it's a true or false value, there isn't a default, but I could make the dev choose
The old save removal is a good suggestion and quite an easy one, I'll add it
And yeah, the pruning might be a little more trickier to implement but actually useful for saveData size
About the importing an imported data... mmhhh.. good question, this actually could be useful in a 3+ chapter game, now what is the answer? Simply clipping any older data (and leave up to the dev how to pass those informations) or enable a layers of old saves? I'll think about it!
Spaces
Ah right, didn't think about the system trimming spaces.
Out of Range
I have "Variable null (never initialized) on Copy old variable" set to err2 (Pass a zero value).
I loaded a save that has 780 variables and then called the plugin function on variable 790 (intentionally going out of bounds). When I trigger the event that loaded the variable, an error is triggered and I get the error message "Error: WD_OlsSaveLoader: Searching for an old variable out of range." So I don't think the settings currently provide any error handling for this scenario.
Actor error handling also does not seem to handle the scenario either (and switches don't have any error handling).