This is an accurate master list for all propositions that give Treasure. The Tactics guide has some of these wrong:

Proposition
City
Cost (Gil)
Job Class
Reward

Hidden Trap at the Maze
Bervenia Free City
8000
Treasure

One Activity
Bervenia Free City
500
Treasure

Minimum’s Melancholy 1
Dorter Trade City
600
Treasure

Minimum’s Melancholy 2
Dorter Trade City
1000
Thief
Treasure

Win the Magic Contest
Gariland Magic City
0
Summoner
Treasure

Miners Wanted 2
Goland Coal City
150
Monk
Treasure

Machinist Contest
Goug Machine City
100
Chemist
Treasure

Salvage the Trade Ship
Goug Machine City
100
Knight
Treasure

Girl at Gulg Volcano
Igros Castle
3100
Knight
Treasure

Ringing of the Bell
Igros Castle
2000
Wizard
Treasure

Theif Zero Reborn!
Igros Castle
5000
Knight
Treasure

Sunken Salvage Tour
Lesalia Imperial Capital
3000
Treasure

Mine Excavation Tour
Lesalia Imperial Capital
1000
Treasure

Theif Zero Returns!
Lesalia Imperial Capital
500
Knight
Treasure

Chocobo Restaurant
Limberry Castle
100
Monk
Treasure

Protect the Little Life
Lionel Castle
1500
Treasure

Emissary of Lionel
Lionel Castle
4000
Treasure

Challenge of Zero
Lionel Castle
50
Knight
Treasure

Sea of Gredia Island
Riovanes Castle
4000
Geomancer
Treasure

Letter to Love
Riovanes Castle
0
Treasure

The Greatest Plan
Riovanes Castle
6050
Treasure

True Romance
Warjilis Trade City
0
Treasure

Miner’s Tour 2
Yardow Fort City
1000
Squire, Knight, Archer
Treasure

Envoy Ship Falcon
Yardow Fort City
3500
Monk
Treasure

Win the Yardow Fight!
Yardow Fort City
0
Knight
Treasure

Zaland Embassy
Zaland Fort City
6000
Treasure

Cliff of Himuka
Zarghidas Trade City
1500
Treasure

Ore of God
Zarghidas Trade City
13000
Treasure

Larner Channel Waves
Zeltennia Castle
3100
Time Mage
Treasure

How Much is Life Worth?
Zeltennia Castle
550
Chemist
Treasure

Phantom Thief Zero
Zeltennia Castle
100
Knight
Treasure