Attacking the Czechoslovak Legion, with all its 20th Century Anabasis energy, does not 'an attack on the Entente' make.
Entente already saw Bolsheviks as very unfriendly - by using German support at first to re-enter Russia, by opposing war and doing separate peace with Germany, by defacto supplying them in the 1918 (this applied to other factions that aligned themselves with Germany too). Many consider them German agents.
Now, it is spring-summer 1918, Germany tries last desperate offensive which may succeed, all fueled by Bolsheviks & others sending tons of materials and relieved military corps from Eastern Europe. And it is worsened by the lack of intel by Entente, with the rumours, suspicions and distrust greatly misportraying situation. The issues aren't a secret, but both sides barely interact due to isolation so the conflict doesn't need to arise.
And then, in tense but slowly normalizing athmosphere Bolsheviks end up trying to attack Czechoslovaks who are bravely fighting for Entente and the corps in Russia intending to do so after the evacuation, respecting the separate peace.
And what is worse, Bolsheviks critically fail with White Russia arising and declaring itself Entente's ally against Bolsheviks that put themselves close to German camp. With huge army similarly having some success liberating Russia from Bolsheviks, largely contributed by Czechoslovaks.
It wasn't a war that Bolsheviks wanted, but they picked up all flags and created an opportunity for Civil War in 1918 out of thin air, right when White Army felt that it had no chances to even start war on Bolsheviks.
And that war, in eyes of Entente, was entirely justified as Bolsheviks were no less appealing to them than Hungary, Turkey, Bulgaria or others.
They sided against Entente and by actions rather than declarations or intentions, so they had to lose.
That's the logic of conflict and especially World War with too much on stakes.
In fact, the fact that Bolsheviks and Atatürk got off so
easily is pretty lucky for them. WW2 didn't take such chances.