How coherence and cohesion parts are evaluated?

Essay topic to essay body coherence: 0.16686713694 0.243740707755 68% => OK
Sentence topic coherence: 0.0533556251524 0.0831039109588 64% => OK
Sentence topic coherence SD: 0.0522985166337 0.0758088955206 69% => OK
Paragraph topic coherence: 0.0982385482316 0.150359130593 65% => OK
Paragraph topic coherence SD: 0.0607550961376 0.0667264976115 91% => OK

My scores of those parts are generally around these range of levles. I would love to enhance this part but I don't know what the problems of mine is exactly, because there are the criteria for coherence and cohesion. I think my paragraph have one topic sentence and several reasons to explain it subsequently. But automatic e-grader always recognizes there are less coherence. Could you tell me what the criteria of this section are, but also how to improve?

for example, this essay topic:

'to understand the most important characteristics of a society, one must study its major cities.'

https://www.testbig.com/gmatgre-issue-task-essays/understand-most-impor…

from the topic, the e-grade is looking for the key words, like: 'understand, society, study, major cities. ' or similar words like: 'know, call...'

so in your paragraphs, it's better to appear those key words to make e-grade satisfied, especially in the topic sentences for main ideas.

Those are main ideas in this essay:

First and foremost, people believe that boonies have well preserved the native custom and culture of a country than concrete jungle). (none of key words in this topic sentence and the paragraph)

However, what was alluded above should not be overgeneralized to all contexts. This is because many major cities nowardays also contain well-conserved cultural heritages or legacy. (better: we see 'major cities')

Secondly, people can familiarize themselves with history in the culturally important places in a major city. (better: we see 'major cities')

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So how to develop better coherences? The answer is: the main ideas should be always around the topic with key words. for example, for this essay topic, we can give some main ideas like:

1. Major cities always are the central of politics, economics and culture of one society, from them, people can know them the past and the future.

2. Major cities are always full of all kinds of people, and it seems reasonable to call a major city as a small society according the whole society.

3. Despite that major cities can be the main factor when considering, but it can't be the solo factor. Because the different development level in different place of the society result in different culture, education, living standard, and so on. So much more detailed information should be considered when someone want really understand the whole society.

4. Major cities would be a best way for one to understand one society, especially when the spirits or fund is limited for the process of understanding, but, more details should be present when to understand the whole society.

5. Nowadays, however, due to the influence of globalization, major cities throughout the world look more or less the same. By contrast, the rural areas of a society maintain more of its cultural tradition.