I confirm it IS an event
SelectFaction = $FRA
SelectRegion = $Gabon
StartEvent = evt_nam_FRA_TekeTreaty1880|1|2|evt_txt_FRA_TekeTreaty1880|Event-img_FRA_TekeTreaty1880|$Gabon|NULL
Conditions
SelectFaction = $CMN
EvalColStatusArea = $Colony_Congo;<;$colProtectorate
MinDate = 1880/09/10
MaxDate = 1899/12/31
Probability = 50
Actions
DescEvent = evt_desc_FRA_TekeTreaty1880
SelectFaction = $FRA
SetColStatusArea = $Colony_Congo;$colProtectorate
ChgVPCount = 100
CreateStruc
SetType = $CONSULATE
SetName = Palais du Résident
Apply
SelectRegion = $Gabon
ChgColonialPen = 50
SelectRegion = $Makokou
ChgColonialPen = 10
SelectRegion = $Mayumba
ChgColonialPen = 10
SelectRegion = $Impfondo
ChgColonialPen = 10
SelectRegion = $Djambala
ChgColonialPen = 10
SelectRegion = $Madingou
ChgColonialPen = 10
SelectRegion = $Nkuna
ChgColonialPen = 10
SelectRegion = $Moanda
ChgColonialPen = 10
EndEvent
problem is it has not been made a protectorate first so move is valid - AI french colonialsim beat you to the finish
- you can consider it as erroneous info from your local colonists, feeding the Kaiser with partial info (hubris, Teutonic arrogance

... I'd tell the same with gallic arrogance would Tanganyka escape your French play ..) you had to hurry up a bit more - that's the roleplay point of view
happened to me in New Guinea Gabon , and had a setback in Nigeria
- or you can make war (I did, you'll be offered impfondo and a lot of uninteresting colonies - SOI wise) - you'll really need a strong warscore to get it
- or add this to your German events
SelectFaction = $GER
SelectRegion = $Gabon
StartEvent = evt_nam_GER_TekeTreaty1880|1|2|NULL|NULL|$Gabon|NULL
Conditions
Actions
SelectFaction = $GER
SetColStatusArea = $Colony_Congo;$colProtectorate
RemoveStruc
SetType = $CONSULATE
Apply
CreateStruc
SetType = $CONSULATE
SetName = ResidentHaus
Apply
SelectRegion = $Gabon
ChangeRgnOwner = FRA
ChgColonialPen = 60
ChangeRgnOwner = FRA
SelectRegion = $Makokou
ChangeRgnOwner = FRA
ChgColonialPen = 20
SelectRegion = $Mayumba
ChangeRgnOwner = FRA
ChgColonialPen = 20
SelectRegion = $Impfondo
ChangeRgnOwner = FRA
ChgColonialPen = 20
SelectRegion = $Djambala
ChangeRgnOwner = FRA
ChgColonialPen = 20
SelectRegion = $Madingou
ChangeRgnOwner = FRA
ChgColonialPen = 20
SelectRegion = $Nkuna
ChangeRgnOwner = FRA
ChgColonialPen = 20
SelectRegion = $Moanda
ChangeRgnOwner = FRA
ChgColonialPen = 20
EndEvent
should work but save your original german events before tinkering with it, always !