"Zsuzsa is walking on the yellow bridge."
Translation:Zsuzsa a citromsárga hídon sétál.
Sarga is the word for yellow. I've never heard lemon yellow being the regular word for yellow.
Yes, that is the common name for yellow. You can use "sárga" and "citromsárga" interchangeably. Also note, the color orange is also a type of "sárga": "narancsssárga". There are other colors that are also "sárga". For example, "aranysárga" (golden yellow). "Sárga" is the generic word for this group of colors, the default meaning being "citromsárga".
Small point but sometimes Hungarian names appear as Hungarian names in the translated English sentence, and on other occasions the English equivalent is used - if indeed there is such a name. The Hungarian name Zsuzsa is sometimes Zsuzsa also in the English, but other times it is translated as Susanna. (Zoltán is always Zoltán of course, as this is a uniquely Hungarian name.) This would not be a problem - except that sometimes one is wrong for not translating Zsuzsa and on other occasions it is accepted. Impossible to guess what approach you are looking for. :)
Is it not also correct to place the color after the noun? Like this: Zsuzsa a hídon sárga sétál.
No, the colour precedes the noun. Red apple is 'piros alma' and not 'alma piros'. Black cat is 'fekete macska' and not 'macska fekete'. So - when we are crossing a yellow bridge, we call it a 'sárga híd'.