The liquid clear is so thick and sticky and takes effort to spread around, I would have some concern that all the brushing it will take to apply it might physically damage the paint film if it's not totally set. How long has it been drying?
In the end it'd probably be okay if you're careful during application of the liquid clear.
You might consider just oiling in with some linseed oil to start your next phase on the painting.
Looking forward to hearing how it goes!