Hi,
I think there is a small bug on displaying derivatives of tensors w.r.t a parameter with a latex_name.
For symbolic expressions,
from sage.manifolds.utilities import ExpressionNice
var('t')
dq1 = function('dq_1', latex_name=r'\dot{q}_1')(t)
L = function('L')(dq1)
ExpressionNice(diff(L,t))
works nicely. However, when I display the same L
as a scalar field (or any tensor),
M = manifolds.Minkowski()
L1 = M.scalar_field(L)
L1.derivative().display()
the latex_name is ignored and dq_1
is used instead. The problem does not occur when there is no index in dq.