The Below code snippet shows how to list all cells from cell libraries. This code browses all the cell libraries located at path "C:\ProgramData\Bentley\OpenRoads Designer CE 10.12\Configuration\Organization-Civil\_Civil Default Standards - Imperial\Cell", this is the default path and may change with the OpenRoads Designer version and workspace and workset user uses. The cell libraries have suffix as .cel

//Required References
using System;
using System.Collections.Generic;
using System.Diagnostics;
using Bentley.MstnPlatformNET;


public List<string> BrowseAllCells()
        {
            List<string> cellList = new List<string>();

            try
            {
                //Get the cell library collection 
                CellLibraryCollection cellLibraryCollection = new CellLibraryCollection(CellLibraryOptions.DefaultAll);
                IEnumerator<CellLibraryInfo> cellLibraryInfos = cellLibraryCollection.GetEnumerator();

                //Iterate each cell library and add cell library name to list
                while (cellLibraryInfos.MoveNext())
                {
                    CellLibraryInfo cellLibraryInfo = cellLibraryInfos.Current;
                    if (!cellList.Contains(cellLibraryInfo.Name))
                        cellList.Add(cellLibraryInfo.Name);

                    //Cell library DGN file and name
                    DgnFile file = cellLibraryInfo.File;
                    String name = file.GetFileName();
                }
            }
            catch (Exception ex)
            {
                Trace.WriteLine(ex.Message);
            }
            return cellList;
        }