What you need to do it update the currentCameraPos each tick. So it should look something like this:
void ATheMeadowsCharacter::Tick(float DeltaSeconds)
{
Super::Tick(DeltaSeconds);
if (isSwitchedCamera == true)
{
FVector currentCameraPos = FMath::VInterpTo(currentCameraPos, cameraTransformA, GetWorld()->GetDeltaSeconds(), 0.5f);
FollowCamera->SetRelativeLocation(currentCameraPos);
isSwitchedCamera = false;
}
}