Why is 真都不错 used here instead of 都真不错?
很 is NOT similar to 真.
很 is used before adj or adv to form a compounded adj or adv phrase, 很 is at the phrase level (inner level). But 真 modifies the whole predicate (ourter level).
We can say:

中国的风景不错。
中国的风景很不错。 很 modifies 不错.
中国的风景真(的)不错. 真 modifies the whole predicate (不错).
中国的风景真(的)很不错. 真 modifies the whole predicate (很不错).

But we can't say:

(NO)中国的风景很真不错. It is wrong because 真 can't be used at the inner level.

We can say:

中国的风景不错。
中国的风景都不错。 都 modifies 不错. inner level.
中国的风景真(的)都不错. 真 modifies the whole predicate (都不错).

But we can't say:

(NO)中国的风景都真不错. It is wrong because 真 can't be used at the inner level.

Please Note: sometimes 真 is also used at the inner level.

他跳得真高. 真 modifies 高.
他真跳得高. 真 modifies the whole predicate (跳得高).
他跳得很高. 很 modifies 高.
他真跳得很高. 真 modifies the whole predicate (跳得很高).

I guess, when only 真 appears, it can be at inner level or outer level. But if there are 2 or more modifiers, then 真 should be at outer level.
Another way to explain this:
很, 都 and 真 work in different aspects.
很 describes to &quot;what extent&quot; the following adj or adv imply. 很 corresponds to &quot;very&quot;, or &quot;very much&quot;.
都 describes the scope the following adj or adv imply. 都 corresponds to &quot;both&quot;, or &quot;all&quot;.
真 emphasizes the following adj or adv.  都 corresponds to &quot;really&quot;.
So the order of them is: 真, 都, 很.

中国的风景不错.
中国的风景很不错.
中国的风景都不错.
中国的风景都很不错.

中国的风景真不错.
中国的风景真很不错.
中国的风景真都不错.
中国的风景真都很不错.