Depends, with our Radar I'm not entirely sure it would have detected the gliders at all.
I'd also suggest we fortify much more heavily, like mines on the beaches if we get the mines, then defensive line of bunkers all along the beach each bunker designed to hold 200-300 men, reinforce it and place reinforced doors inside it to make attacking it far more difficult, then we have AA emplacements on the roof, Artillery batteries a mixture of long range and AT guns and attach a series of Pillboxes around the outside of it as well as more MG on the main building itself.
Then dig a trench from each line to the one behind it, that way reinforcements can move with cover but place a couple of MG to cover it so if the enemy tries to use it then the trench line doubles as a killing field.
Oh we should also dig a big series of pits and set up tank traps all along the beaches to make sure next time we can funnel the armor into the AT mines and make attacking a damn sight harder for them.
Repeat this every 3 miles or so back and the island will take weeks just to manage to push inland giving us much more time to react and making things bloody as all hell for the enemy.
It'll be expensive as hell but this attack is going to happen in every war we fight sooner or later so we may as well turn Crow into one huge fortress island rather then just building a fortress on it or we're gonna end up repeating this counter attack every time we go to war.
We're still the smallest nation except 1 so we can't rely on being able to beat the enemy before he attacks us so Crow needs to be heavily enough fortified that it will be more effective to besiege it then attack it to make sure it holds out a long time. Might be worth adding some concealed artillery positions, that way when we counter attack we can unleash a massive amount of artillery on the enemy fleet.
I'm not a big fan of defense, but when a defensive position is needed I always find it better to make sure the position has the general effect of making enemy soldiers say OMFG I am not attacking that place.