I have the same poi icon problem.
Is the source code broken, column numbers mismatch?

drawing poi using column 2 (poi label) and 5 (cat label):
...
gchar *poi_label = g_utf8_strdown(sqlite3_column_text(
_stmt_select_poi, 2), -1);
gchar *cat_label = g_utf8_strdown(sqlite3_column_text(
_stmt_select_poi, 5), -1);

initializing the select statement, column 4 is poi label and 7 is cat label:
...
sqlite3_prepare(_db,
"select p.lat, p.lon, p.poi_id, p.label, p.desc,"
" p.cat_id, c.label, c.desc"
" from poi p, category c "
" where p.lat between ? and ? "
" and p.lon between ? and ? "
" and c.enabled = 1 and p.cat_id = c.cat_id",
-1, &_stmt_select_poi, NULL);

...