Are there any immediate issues concerning vinyl siding over Composition (T1-11). Florida install on the water.
Only if your AHJ says there is.
In my ‘town’ you have two options… if there is damage to the ‘underlayment’ i.e. ‘rot’… 1) it (rot) must be completely repaired prior to the vinyl being installed, or 2) it (original siding) must be completely removed prior to the vinyl being installed.
Note: There are also insulation requirements due to our extreme weather cycles.
As long as the base material T1-11 was in sound condition before applying the vinyl siding, it should not be a problem.