A project has various constraints on captions. CaptionHub will warn you if your translation doesn’t satisfy them. These constraints include:
Character length per line
The maximum number of characters in a single line of a caption. (Captions may have one or two lines, depending on the "Number of lines" limit. If you exceed the allowed amount, the character count for that line will turn red:
Number of lines
The number of lines in a single caption. If this is exceeded, the entire caption box will turn red. Careful: an extra carriage return (new line) at the end of the caption will add an extra line, which might cause errors.
The minimum time a caption can appear on screen for. The original caption set has been set up with all captions at least the correct length. Should you alter the timings, any caption that lasts less than the minimum duration will turn red in the timeline: