Been there, done that. I've also already removed bunique.That is strange. Maybe remove <NativePlane> from your code?
You know what, I'll simply copy&paste one of the improvements here, it's not THAT long:
<ImprovementInfo>
<Type>IMPROVEMENT_EXPLORED_TOWER_OF_EYES</Type>
<bForceOverwrite>1</bForceOverwrite>
<Description>TXT_KEY_IMPROVEMENT_TOWER_OF_EYES</Description>
<Civilopedia>TXT_KEY_IMPROVEMENT_TOWER_OF_EYES_PEDIA</Civilopedia>
<Help></Help>
<ArtDefineTag>ART_DEF_IMPROVEMENT_TOWER_OF_EYES</ArtDefineTag>
<YieldChanges>
<iYieldChange>0</iYieldChange>
<iYieldChange>0</iYieldChange>
<iYieldChange>0</iYieldChange>
</YieldChanges>
<bActsAsCity>0</bActsAsCity>
<bHillsMakesValid>0</bHillsMakesValid>
<bFreshWaterMakesValid>0</bFreshWaterMakesValid>
<bRiverSideMakesValid>0</bRiverSideMakesValid>
<bNoFreshWater>0</bNoFreshWater>
<bRequiresFlatlands>1</bRequiresFlatlands>
<bRequiresRiverSide>0</bRequiresRiverSide>
<bRequiresIrrigation>0</bRequiresIrrigation>
<bCarriesIrrigation>0</bCarriesIrrigation>
<bRequiresFeature>0</bRequiresFeature>
<bWater>0</bWater>
<bGoody>0</bGoody>
<bPermanent>1</bPermanent>
<iAdvancedStartCost>-1</iAdvancedStartCost>
<iAdvancedStartCostIncrease>0</iAdvancedStartCostIncrease>
<iTilesPerGoody>0</iTilesPerGoody>
<iGoodyRange>0</iGoodyRange>
<iFeatureGrowth>0</iFeatureGrowth>
<iUpgradeTime>0</iUpgradeTime>
<iAirBombDefense>0</iAirBombDefense>
<iDefenseModifier>0</iDefenseModifier>
<iHappiness>0</iHappiness>
<iPillageGold>0</iPillageGold>
<bOutsideBorders>1</bOutsideBorders>
<TerrainMakesValids>
<TerrainMakesValid>
<TerrainType>TERRAIN_GRASS</TerrainType>
<bMakesValid>1</bMakesValid>
</TerrainMakesValid>
<TerrainMakesValid>
<TerrainType>TERRAIN_PLAINS</TerrainType>
<bMakesValid>1</bMakesValid>
</TerrainMakesValid>
<TerrainMakesValid>
<TerrainType>TERRAIN_DESERT</TerrainType>
<bMakesValid>1</bMakesValid>
</TerrainMakesValid>
<TerrainMakesValid>
<TerrainType>TERRAIN_MARSH</TerrainType>
<bMakesValid>1</bMakesValid>
</TerrainMakesValid>
<TerrainMakesValid>
<TerrainType>TERRAIN_SWAMP</TerrainType>
<bMakesValid>1</bMakesValid>
</TerrainMakesValid>
</TerrainMakesValids>
<FeatureMakesValids>
</FeatureMakesValids>
<BonusTypeStructs>
<BonusTypeStruct>
<BonusType>BONUS_MANA_MIND</BonusType>
<bBonusMakesValid>1</bBonusMakesValid>
<bBonusTrade>1</bBonusTrade>
<iDiscoverRand>0</iDiscoverRand>
<YieldChanges>
<iYieldChange>0</iYieldChange>
<iYieldChange>0</iYieldChange>
<iYieldChange>0</iYieldChange>
</YieldChanges>
</BonusTypeStruct>
</BonusTypeStructs>
<ImprovementPillage></ImprovementPillage>
<ImprovementUpgrade></ImprovementUpgrade>
<TechYieldChanges>
</TechYieldChanges>
<RouteYieldChanges>
</RouteYieldChanges>
<bGraphicalOnly>0</bGraphicalOnly>
<bRequiresPeak>0</bRequiresPeak>
<bUnique>0</bUnique>
<iAppearanceProbability>0</iAppearanceProbability>
<iHealRateChange>0</iHealRateChange>
<iRange>0</iRange>
<iRangeDefenseModifier>0</iRangeDefenseModifier>
<iVisibilityChange>6</iVisibilityChange>
<BonusConvert>BONUS_MANA_MIND</BonusConvert>
<FeatureUpgrade>NONE</FeatureUpgrade>
<PrereqCivilization>NONE</PrereqCivilization>
<PythonAtRange></PythonAtRange>
<PythonOnMove></PythonOnMove>
</ImprovementInfo>
If I use this, I get the tower all over the map. If I put bunique in, I only get it once, but that's still one time too much.