Besides the obvious B.534 which was the main Czech fighter and S.328 as a light bomber/recce you can also use the SB as a stand-in for Avia B.71 bombers which were in fact license-built Tupolev SB's but with Hispano-Suiza inline engines and modified equipment and armament.
I don't think PZL.37 would be a particularly good fit as a stand-in for any Czech pre-war type.
Here is a list of the most important types in the pre-war Czech Air Force inventory:
Fighters:
Avia BH.33 - biplane fighter, thoroughly obsolete, being phased out
Avia B.534 - biplane fighter, arguably the best in the world, built in 4 distinct subtypes - the one we have in the game is the IV series with enclosed cockpit, the earlier versions had open accomodation; the main fighter in the Czechoslovakian Air Force
Avia Bk.534 - cannon-armed development of B.534 (engine-mounted Oerlikon 20mm + 2 machineguns) unfortunately very few were delivered with the cannon installed, usually they had another machinegun in its place
Letov S.231 - another biplane, fairly modern, was built in lesser numbers to complement the B.534's
Avia B.35 - only a handful of prototypes built before the German takeover, this was a true modern monoplane design with retractable gear and enclosed cockpit, it was supposed to start replacing the biplane fighters as soon as the full production line was set up
Light bombers and recce:
Aero Ap.32 - reconnaissance biplane and army cooperation plane with a secondary light bomber role; built in fairly small numbers and being phased out
Aero A.100 - light bomber and reconnaissance biplane, built in small numbers, still operational at the time of German takeover
Aero A.101/Ab.101 - enlarged version of the A.100, the original A.101 was a failure but with upgraded engine as Ab.101 it offered similar performance as the A.100.
Letov S.328 - another light bomber/recce biplane, already in game
Multi-engined aircraft:
Avia B.71 - license-built Tupolev SB with locally produced engines and equipment; Main bomber in the Czech arsenal
Aero A.304 - twin engined monoplane fast reconnaissance / light bomber developed from an unsuccessful airliner design; just about a dozen built before the German takeover
Aero A.300 - a modern fast bomber prototype developed from A.304; showed great promise but all development stopped after German takeover
Aero MB.200 - license-built French Bloch MB.200 twin-engined "heavy" night bomber, already thoroughly obsolete
Avia F.39 - three-engined heavy transport/bomber based on the Fokker F.IX airliner
Avia F.VII - license-built Fokker F.VII airliner/transport/bomber, being phased out in favor of F.39
That's pretty much it...