How do I translate these criticisms about Australia by Chinese netizens? E.g., 我实名不满澳大利亚，狗腿子一个！还有脸说没听过。
Well, usually this kind of disputes passes very soon (e.g. Japan-China), and I hope it's the case here. The comments in these contexts can be genuine or simply agitators looking to get likes by exploiting the situation.


实名不满/实名反对/实名举报 is not a typo. It means to express dissatification/opposition or raise complaint "openly with real name". 实名举报 came first as a complaint with real name is considered stronger than an anonymous one; and it can be dangerous, especially under a less transparent/democratic government and government censorship.

It can be used even if you are using a pseudoname online as a generic emphasizer in saying that you are not an astroturf account; this is your real opinion; you are unshamed and unafraid to have this opinion.

狗腿子 is close in meaning to 走狗 running dog.
The well is referring to the tale of a frog in a well (https://en.wikipedia.org/wiki/Kupamanduka), meaning a person (the frog) has narrow perspectives since they can only see the world from the opening of the well (as they are at the bottom of the well).

The use of 无懈可击 here is sarcastic, saying the reasoning of the previous sentence (by Australians presumably) is so "strong" (akin to "I can't even argue with this logic!!").

I think the poster was trying to say the logic for "The reason for criticizing China's web as not open is he believes online views are fake" is kind of circular. But I'm having trouble to comprehend the sentence (I can understand the semantics but not the logic).
It is a reference to Jiang Zemin (see https://en.wikipedia.org/wiki/Toad_worship, not an ideal article, but good enough for overview; most English articles on Chinese online subcultures are too ideologically driven, it's better to just participate in Chinese online communities and learn by immersion):


  In the first video, Jiang lashed out at Hong Kong journalist Sharon Cheung in Zhongnanhai when he met with Chee-hwa Tung, Chief Executive of Hong Kong at that time. Ms. Cheung asked if Jiang supported Tung's campaign for Chief Executive, which Jiang affirmed. Cheung then asked if it meant the Chinese government had already decided internally to re-appoint Tung. This made Jiang very upset, and criticized her for twisting his words to "make big news." Jiang then continued to criticize the Hong Kong media on the whole, claiming that they need to learn to ask more meaningful questions, even stating that "Mike Wallace of the US is at a much higher level than you are."


Here is the Chinese Wikipedia article on the incident. The original quote from Jiang was:


  你们啊，不要想……喜欢……这…欸弄个大新闻，说现在已经钦定了，再把我批判一番。
  You guys...Don't...[You guys] Like to make a big news, saying [the choice of Chief Executive] is already decided [by the Central government], and then [you will again] criticize me.


The poster is criticizing the Australian journalists are trying to "make a big news (out of nothing)". I think [并不简单] is an emoji transcription (?) not meaningful without the actual emoticon. (After all,  is sometimes just transcribed as "joy", which doesn't capture the full meaning) 
"Robots" as in astroturfing accounts. Consider the fictionary (but based on a thread I actually read) following exchange on Twitter:


  
  A: I support Bernie Sanders, don't vote for Joe Biden!!
  B: You are a Russian bot!!!
  A: Sure I am a Russian bot, no Amercian ever likes universal public healthcare.
  


This is what the poster was trying to do here. I'm not sure what this kind of "arguing" technique is called.
I think your translation works, or just "[I] have never seen such a shameless journalist."