acceptability of Chinese-Traditional character substitute

["Boncek, John" <jboncek hunter com>]

On an embedded Linux / GTK 2.10 / Pango system with limited font and memory resources, we have CJK font support via the latest release of X11R7.3, using only the "misc-misc" fonts.  We have found a missing character, U+555F.  The online Unihan database at

 

http://www.unicode.org/cgi-bin/GetUnihanData.pl?codepoint=555F&useutf8=false

 

shows this character to have a "semantic variant" U+5553.  Would it be considered acceptable to programmatically replace the missing character with this one?  I know this is not an ideal solution.  If this is not considered acceptable, can you suggest some other solution?  Adding one of the massive CJK fonts like Wen Quan Yi is not an option for this system.  Thanks for your attention.