The questions asked about race and ethnicity have varied over the years. It can be difficult to get the level of detail needed because of population thresholds. For example, if you are trying to find the number of Marshallese people in Waimanalo, the information is not available because the population threshold for release of detailed race/ethnicity categories is 500,000, and only Honolulu County and the State of Hawai`i surpass the threshold.
Like race and ethnicity, language spoken at home is subject to population thresholds. As a result, information about specific languages may only be available at the County or State level, but not for Census-designated places or smaller geographic units.
The census is a survey based on addresses, because its primary purpose is the apportionment of Congressional districts. Homeless people who live in shelters or transitional housing are counted in Census surveys, but people who do not have addresses are not counted. As a result, the homeless population must be calculated using special surveys done by cities or states. Read more about the homeless population in Hawai`i here.
State data centers partner with the Census Bureau to promote Census surveys and provide access to Census data. In Hawai`i, the Department of Business, Economic Development, and Tourism is a State Data Center affiliate. They perform tabulations and provide access to a wealth of Census data from several different surveys.
Links to other State Data Centers: https://www.census.gov/about/partners/sdc/member-network.html