How to handle a large amount of very specific use cases

You can approach problem from opposite direction.
Create type with two functions, one for running test and another which check is test need to be run.

public class Test
{
    public Action Run { get; set; }
    public Func<bool> CanRun { get; set; }
}

Then you simply define all tests with their own predicate

var test1 = new Test
{
    Run = () => runtest1(param a, param b),
    CanRun = () => radiobutton1.checked && checkbox1.checked
};
var test2 = new Test
{
    Run = () => runtest2(param b, param f),
    CanRun = () => radiobutton1.checked && checkbox1.checked
};
var test3 = new Test
{
    Run = () => runtest1(param f, param n),
    CanRun = () => radiobutton1.checked && checkbox2.checked
};
var test4 = new Test
{
    Run = () => runtest2(param c, param l),
    CanRun = () => radiobutton1.checked && checkbox2.checked
}

// Then tests execution will looks much simplier
var testsToRun = 
    new[] { test1, test2, test3, test4 }.Where(test => test.CanRun());

foreach (var test in testsToRun)
{
    test.Run();
}

Approach above should make maintenance easier, where every test is isolated from others, when adding or removing tests you don't need to touch code related to other tests.