Do you have cloister-phobia?

None here. The opposite of cloisterphobia is roisterphobia and the oft concomitant affliction boisterphobia. The clammy consequence of oisterphobia is however unrelated.

Fear of a cloister of nuns is completely understandable.
Opposite would be demons, or minions.
Not sure which I’d find scariest actually!

Agraphobia?

^^^ I put it to you that you are confusing the stated topic with claustrophobia/agoraphobia.

@RedDeerGuy1 “info on this obscure phobia?”

Browning’s Soliloquy of the Spanish Cloister provides a mere morsel of insightful historicity in its mealy-mouthed meandering. For sheer pertinence I muchly prefer:

Obloquy of the Mannish Foister

Oh, those melons! when she’s able
They do form a feast; so nice!
Both go to the Abbot’s table,
All of us get not a slice.
How go on your flowers? None double?
Not one fruit-sort can you spy?
Strange!—And I, too, at such trouble,
Keep them close-nipped on the sly!