How to insert several csv files into Elasticsearch?
I just had a look at the data in the Higher Education Statistics Agency (HESA) zipped file and the files are all different.

This means you will either have to create an individual .config file for each import or create a single .config file using conditions as described in the following article:

Reference: How to use multiple csv files in logstash (Elastic Discuss Forum) 

Expanding on your first .config by one level:

input{
    file{
        path =&gt;"Users/mike/Data/ACCREDITATION.csv"
        start_position =&gt; "begining"
        sincedb_path =&gt; "/dev/null"
    }
    file{
        path =&gt;"Users/mike/Data/ACCREDITATION.csv"
        start_position =&gt; "begining"
        sincedb_path =&gt; "/dev/null"
    }

}

filter{
    # added condition for first file
    if [path] == "Users/mike/Data/ACCREDITATION.csv"{
        csv{
            separator =&gt; ","
            columns =&gt; ['PUBUKPRN', 'UKPRN', 'KISCOURSEID', 'KISMODE', 'ACCTYPE', 'ACCDEPEND', 'ACCDEPENDURL', 'ACCDEPENDURLW']

        }
        mutate{convert =&gt; ["PUBUKPRN","integer"]}
        mutate{convert =&gt; ["UKPRN","integer"]}
        mutate{convert =&gt; ["KISMODE","integer"]}
        mutate{convert =&gt; ["ACCTYPE","integer"]}
        mutate{convert =&gt; ["ACCDEPEND","integer"]}
    }
    # added condition for second file
    else if [path] == "Users/mike/Data/AccreditationByHep.csv"{
        csv{
            separator =&gt; ","
            columns =&gt; ['AccreditingBodyName', 'AccreditionType', 'HEP', 'KisCourseTitle', 'KiscourseID']
        }
    # ommitted mutations for second file
    }

}

output{
    # added condition for first file
    if [path] == "Users/mike/Data/ACCREDITATION.csv"{ 
        elasticsearch{
            hosts =&gt;"localhost"
            index =&gt;"accreditation"
            document_type =&gt;"accreditaiton keys"
        }
    }
    # added condition for second file
    else if [path] == "Users/mike/Data/AccreditationByHep.csv"{
        elasticsearch{
            hosts =&gt;"localhost"
            index =&gt;"accreditationByHep"
            document_type =&gt;"accreditaitonbyhep keys"
        }
    }
    stdout{}
}


document_type is a deprecated configuration option

You should be able to expand on this example on your own.