Linear Actuator Clicking
As both the LXF file and the video are unavailable, I can only guess at the problem you are facing. But if the linear actuator is clicking, it means the built-in clutch is engaging, as the forces keeping the actuator from moving are too large. This can't be solved by adding a clutch gear (even with gearing), as if the newly added clutch gear is rated to slip at a lower force, it will slip before the linear actuator, and if it starts to slip at a larger force, the linear actuator will still start clicking first.
The best way would be to redesign the linkage to require less force to operate, but it might not be possible in your case:

To save space, I insisted on having a fixed, almost parallel LA

This rules out another possible solution: doubling the linear actuators involved, as two parallel linear actuators will start clicking at a doubled force.
The only remaining advice I can give is to reduce the forces involved, either by attempting to redesign the linkage, or incorporating other means to provide force to assist the linear actuator, like springs, rubber bands, torsion bars, flexible elements, pulleys or even counterweights.