if (name == "CUSTOM CI ID Attr")

    "[" + value + "]"
}
else
{
    ""
}

This adds a custom CI prefix to the id of the artifact in the requirement spec; for example

[80211-SRS-83889]

You are right. You need to iterate twice - once to check for condition and then again to conditionally print the data. However, if you have a module view with filter, you can report directly on view (using "views" data source). Starting from DNG 6.0.4, you can execute external requests against views artifact format and create RPE templates based on views data source schema.
Requests against DNG reporting service for "views" artifact format are supported under the following formats:
https://serverName:port/rm/publish/views?moduleURI=https://serverName:port/rm/resources/_YbK4wd6IEeaEaOW7hUvrNQ&viewURI=https://serverName:port/rm/views/_iRsR8d6IEeaEaOW7hUvrNQ&projectURI=serverName:port/rm/process/project-areas/_uxdv8N3FEeaRC8I0G_Qhlg

or

https://serverName:port/rm/publish/views?moduleURI=_YbK4wd6IEeaEaOW7hUvrNQ&viewURI=_iRsR8d6IEeaEaOW7hUvrNQ&projectURI=_uxdv8N3FEeaRC8I0G_Qhlg

Note: To be able to execute an external request against "views" artifact format, project area, module and view information is necessary and view and module must belong to the project area provided on the request. If one of these parameters (moduleURI, viewURI and projectURI) is missing or invalid, or module or view do not belong to the project area, then a bad request response will be provided.

Apart from the 2 templates shipped with RPE, you can also find few RPE templates in DNG install path (under JazzTeamServer\server\conf\rm\reporting\initialization\templates\rrdg). You can refer to printModuleBook.dta, which uses views data source schema.