Exponentiation In PBC library
I don't think $h^l$ where l is a float number is a well defined operation in a finite group, regardless of what context you want to use this group for.
A group is a set of elements G with a binary operation $\cdot$ (multiplication) defined, often denoted as (G,$\cdot$) satisfying four properties. You can find more information here: http://mathworld.wolfram.com/Group.html.

Then, exponentiation is defined as repeating multiplication on a group element a certain number of times. For example, $h^n=h\cdot h\cdot h \cdot ... \cdot h$ (repeating $n$ times). So you should be able to see that for example repeating multiplication 3.1415956 times is not well defined.

Specifically, for pairing, G2 is a group over the twist curve. In this group, one operation is defined. Usually, this operation is called point addition. However, in PBC, if you look at the document, it is said that "The addition and multiplication functions perform addition and multiplication operations in rings and fields. For groups of points on an elliptic curve, such as the G1 and G2 groups associated with pairings, both addition and multiplication represent the group operation (and similarly both 0 and 1 represent the identity element). It is recommended that programs choose and one convention and stick with it to avoid confusion." (http://crypto.stanford.edu/pbc/manual/ch04s04.html).

So, the operation you are talking about is not well defined.