minor yogurt spill on keyboard

3 months ago i dropped 2-3 drops of greek yogurt on mba4 keyboard. i cleaned it up and turned the mac off for a bit, and later there was no visible damage or malfunctioning except that the key it fell on, the backlight for that key is noticeably brighter than the rest. no other aspect of performance has been affected. i took it to the apple store and since i dont have applecare+ theyre saying itll cost usd500 to repair since theyll have to repair the entire keyboard and backlight, and this is more than half what i bought the laptop for.

my only question is- i dont mind the backlight being brighter, but what are the chances that this leads to corrosion of the logic board down the line? and what will happen if it does? its been 3 months and there have been no problems other than the brightness, so is there even a chance there’ll be further problems with the device’s performance later? because if not i dont think its worth paying half a grand to repair😅