if present perfect, followed by would

[ostap77]

"If Pluto has just been discovered, there's no doubt that it wouldn't be termed a planet."

Is this sentence grammatical?

 

[Tdol]

I would use had just been discovered. Has sounds wrong to me.

 

[ostap77]

I would use had just been discovered. Has sounds wrong to me.

Would that be a major mistake in conversation or one of those that would only be noticed by teachers?

 

[5jj]

Would that be a major mistake in conversation or one of those that would only be noticed by teachers?

It is something that native speakers just wouldn't say, and they would notice it if a learner said it, in my opinion.