A bunker generates a warning when it is unable to convert a piece of data to match InfoSum's Global Schema. While it may not be possible to eliminate all warnings, resolving those which can be addressed will improve the quality of your dataset and the accuracy of your results.
You can search for warnings using your bunker's web UI, either by using the Sort by warnings feature or simply by looking for cells which are shaded red.
Some warnings may reflect fundamental problems with the original data, such as missing information or obviously inaccurate details. The only way to resolve this type of warning is to improve and re-import your original data.
Other warnings, however, may be due to a mismatch in format between your imported data and InfoSum's Global Schema. In this case, you can use mappings and transformations to resolve the problem. Typically, this will improve your representation fill rate.