Relevancy is the key to search engine optimization brought about by the right contents, right submission process and equally matched by design and functionality.
The search engine offer relevant answers to queries submitted by the user. This is their job..provide what the users seek.
In the complex process of indexing and ranking the website is evaluated using hundreds of matrix many of which are not known to webmasters let alone the users. But a common sense approach is what furnishes results to the web owners made possible by webmasters.
In local search the website internal architecture and contents point towards a specific region. Most of the submissions are made in local directories. The site is further aided by the use of meta data and snippets.In this case it is good idea to host the website on local IP provided by the hosting company.
Some sites tend to be useful to local area as well as larger global audience. If the site is meant for a specific country the language used should be that used by most. In case of a resource with pages in different languages the alternate tag below is used to inform the search engines.
<link rel="alternate" href="http://example.com" hreflang="en-us" />
Not all elements on page are used to augment rankings but the usefulness of the above tag is obvious. These are the element which increase relevancy and usefulness and hence increase conversion. This way one can also reduce bounce rate hence have a positive effect on rankings too.
Using country specific TLC or domain is the best practice. But on oft occasions this may not be possible hence one can create a sub-domain in order to furnish the user with preferred language. Creating sub directories and silos are another possible methods.
If no solution is possible due to resource constraints than in that case use the translator to help users read contents in language they understand.