For 1.5.x You will find some CSS fixes for some pages here:
For most pages it is better to use 1.6.beta2 en-US and identify UserAgent ID as a Firefox 3.6 version. Install this version in separate folder with new name like
./Programas/K-Meleon1.6.beta2 en-US and not into folder with default name
"K-Meleon". ALL 1.5 and 1.6 versions can use each others profiles.
To have most (but not all) menues in Spanish with 1.6 You copy locales folder from 1.5.4es-ES to K-Meleon 1.6 folder, restart the browser and set language to Spanish under F2 -> Gui Appearance -> Language.