[chc]

I think that's more a peculiarity of Russian than a necessary quality of flexible sentence order. For example, many deviations from the standard sentence order in Japanese can still be understandable and grammatical because particles denote the parts of the sentence.

[eimrine]

I don't speak Japanese, but you are talking about fixed order, allowing deviations. Russian language doesn't have this kind of deviations because of there is no order at all. If you take any Russian sentence (better not to take a too long one) and mix words in random sequence, the sentence became mostly the same but with other words nuanced.

Roughly example of conception of "other word nuanced" from Russian:

1. explosion happened - I waited for the explosion and it happened.

2. happened explosion - I waited for arriving of my girlfriend but what arrived first is the explosion.