The board observer's report is considered confidential. It does not need to be long or all-encompassing, but it should give a sense of how successful the event or project was. In general, include in your report whatever you think would be valuable to the evaluation of future grant requests by the same organization. Some of the things you might consider including are:
Email your board observer's report, marked CONFIDENTIAL, to the HI Board listserv, or send it directly to the grants director (tim-johnson(at)uiowa(dot)edu). In either case, the report will be added to the grant file and will be summarized in the staff comments on future grant requests from the same organization.