Hello,
Try to open .graphml files in Gephi, and then exporting then to spreadsheets (.csv, you can choose the delimiter): https://gephi.org/
It requires JavaRE 1.8 or higher installed.
For Java 32 bits, try running:
\Program Files\Gephi-0.9.2\bin\gephi.exe
instead of gephi64.exe, which runs only with Java 64 bits.
Troubleshoot: https://github.com/gephi/gephi/issues/1787
It worked on a simple test.
Hope it can be useful.