Why can't I sort by Cost/Conv or a ratio metric?
The reason why sorting by absolute ratio metrics isn't available is because doing so won't give you an idea of the volume of traffic a search term received. For example, a search term may have had a very low cost/conversion but this could be because it just received one conversion. If the Word Cloud were to sort based on cost/conversion, this search term would show up prominently and would appear to be performing very well, despite there not being enough conversions to make a decision on its actual performance.
We understand that ratio metrics are important, and that is why we have the option to show two metrics in the word cloud. To show search terms by cost/conversion, select Cost as the metric to sort by (highlighted by size) and then conversions as the second metric (highlighted by color). When this happens, you'll see that the search terms that are big in size, but light in color have a high cost/conversion (high cost but low conversions), and the search terms that are small in size but dark in color have a low cost/conversion.
Are the search terms from Shopping Campaigns also included Search Terms N-grams tool?
The Search Terms N-Grams is based on Search Terms report which also contains the search terms which triggered the Shopping Ads. If you want to look at search terms of a Shopping campaign only, you can segment the search terms for which the data is being aggregated in the word cloud by that particular campaign.
The conversion column shows more conversions than I actually have
The Search Terms N-Grams breaks down each search term into individual words and aggregates data from each of these individual words occurrences in the search terms report. That's why when you sort by 1 individual N-Gram, the Conversions you visualize will be higher than your actual Conversions.
For example, if a query is 10 terms long, the tool will break it down into ten individual words and aggregate data like impressions, clicks, conversions, converted clicks for all the times that the word occurred in the report.