Acorn vector graphics files (.aff) are still supported in some of the graphics editors, including CorelDraw and as such the only viable way to edit this graphics. Alternative would be find at least a viewer for .aff files and print it as PDF document with a virtual PDF printer installed.
Convert Acorn vector draw file to Adobe Portable document format.
We found one software available in the database for this conversion.
Microsoft Windows software - convert aff to pdf on Windows
A set of applications used by professional graphic designers
Convert from aff file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.