Here are my picks (with a few extras in some categories).

6 countries

Finland (Hatching)✅
Denmark (The Innocents)✅
Canada (Crimes of the Future)✅
Piggy (Spain)✅
Germany (The Cabinet of Dr. Caligari)✅
UK (Saint Maude)✅

8 decades

1920s (The Cabinet of Dr. Caligari)✅
1950s (Dracula)✅
1960s (The Devil Rides Out)✅
1970s (Let’s Scare Jessica to Death)✅
1980s (The Hunger)✅
1990s (Troll 2) ✅
2000s (The House of the Devil)✅
2020s (The Innocents)✅

2 insect centered films

The Giant Spider Invasion✅
The Fly✅

1 horror film set in space or the future

Crimes of the Future✅

2 animated films

A Creepshow Animated Special✅
Birdboy: The Forgotten Children✅

1 bloodthirsty old person/people film

X✅

2 1970s regional US films

Children Shouldn't Play with Dead Things✅
Let's Scare Jessica to Death✅
I Drink Your Blood✅
Shock Waves✅

The worst horror sequel from the 1990s that you haven't seen and can access.

Troll 2✅

1 German Silent

The Cabinet of Dr. Caligari✅

5 Films from David Cronenberg, Ti West, Bill Rebane, Charles B. Pierce, William Grefe and/or Joy N. Houck Jr.

X (West)✅
The Giant Spider Invasion (Rebane)✅
Crimes of the Future (Cronenberg)✅
The Fly (Cronenberg)✅
The House of the Devil (West)✅
The Innkeepers (West)✅

2 Christopher Lee films 

The Devil Rides Out✅
Dracula✅

1 film with a musician or band in it (A real life musician or band)

The Hunger✅
Studio 666✅

1 Stephen King adaptation that is not the first go around.

Carrie✅

1 Lon Chaney film. (NOT JR)

The Phantom of the Opera✅

1 Tobe Hooper Film

Poltergeist✅

**EXTRA:
The Last Circus ✅
Silent Madness✅
Pennywise: The Story of It.✅