Your issue is not to do with punctuation, it is more to do with using the field names within the field text, e.g. Project:
If you know the field names you want to extract, you could do something like this
| makeresults
| eval _raw="description=\"User: ABC Project: XYZ Company Name: JKLM Short Description: Project is so and so\"
description=\"User: ABC Company Name: JKLM Project: XYZ Employee Level: 7 Short Description: Project is so and so User Designation: Splunk Consultant\"
description=\"User: ABC Project: Jkl Company Name: JKLM Short Description: Project: Automation\""
| multikv noheader=t
| fields _raw
| fields - _time
| eval raw=_raw
| rex mode=sed field=raw "s/User: /_User_: /g"
| rex mode=sed field=raw "s/Project: /_Project_: /g"
| rex mode=sed field=raw "s/Company Name: /_Company Name_: /g"
| rex mode=sed field=raw "s/Employee Level: /_Employee Level_: /g"
| rex mode=sed field=raw "s/Short Description: /_Short Description_: /g"
| rex mode=sed field=raw "s/User Designation: /_User Designation_: /g"
| rex mode=sed field=raw "s/_(?<first>[^_]+)_: _(?<second>[^_]+)_/_\\1_: \\2/g"
| rex max_match=0 field=raw "_(?<namevalue>[^_]+_: [^_]+)"
| mvexpand namevalue
| rex field=namevalue "(?<name>[^_]+)_: (?<value>[^\"]*)"
| eval {name}=trim(value)
| fields - name namevalue value raw
| stats values(*) as * by _raw
Note that where Project: was used at the beginning of the field, this was corrected by assuming every field had something in and that if a known field name was at the start of the field, it could be reverted back to just text and not a field name to extract. Also, there is an assumption the underscores aren't used in the text. If they are, then use something else (that isn't in the text) as a delimiter for the field names.
