The answer is in this text, but I shall simplify it to make it more evident.
The text is:
Reserves grow at the same rate as life force when you are below the maximum, do not grow at all when your life force is not at max, and can never go above the life force reserve maximum, which is currently set at 10x your max life force.
The simplified answer to your question, taken from the text is:
Reserves [...] can never go above the life force reserve maximum [...]
OR
Reserves grow at the same rate as life force when you are below the maximum, do not grow at all when your life force is not at max, and can never go above the life force reserve maximum, which is currently set at 10x your max life force.