Should that happen

[Offroad]

Dear friends

Am I right with the following interpretation?

We must protect the village against those people. They are too dangerous and may very well destroy all our work. Should that happen. I'll feel obligated to set up a plan to destroy theirs too.

Should that happen = if that happens.

I wonder if it's idiomatic.

Thank you.

[Gillnetter]

Dear friends

Am I right with the following interpretation?

We must protect the village against those people. They are too dangerous and may very well destroy all our work. Should that happen, I'll feel obligated to set up a plan to destroy theirs too.

Should that happen = if that happens.

I wonder if it's idiomatic.

Thank you.

Yes, you used it correctly but what you will destroy is unclear. Note that I put a comma after "happen", not a period.

[AlexAD]

Not a teacher, nor a native.
I would also replace a full stop with a comma there.
Should that happen = if that should happen, that is nearly the same as if that happens, but with should, the speaker feels that the possibility is smaller.
I can see that idiomatic means both expressions that contains idiom and expressions that are natural to native speaker.
Not knowing which of these you meant, I can give you an example I came across reading a brochure:
Should you become a victim of a crime, call some number.
So I guess it is natural to native speakers.

[5jj]

I would also replace a full stop with a comma there.
Should that happen = if that should happen, that (either '... happen. That ...' or '... happen, which ...') is nearly the same as if that happens, but with should, the speaker feels that the possibility is smaller.
I can see that idiomatic means both expressions that contains idiom and expressions that are natural to native speaker. (unfortunately that sentence is not natural. 'Both expressions are idomatic and natural' is shorter and simpler.)
Not knowing what which of these did you meant, I can give you an example I came across reading a brochure:
Should you become a victim of a crime, call something (someone?).
So I guess it is natural tonative speakers.

5