If this sentence beginning "Asimismo" mentions only one law, the plural "resultan" is clearly an error and should be "resulta". It may be that whoever drafted this expected to mention more than one law or decree in this sentence, and then forgot to change it to the singular when there turned out to be only one, or it could simply be a typo. You could mention the anomaly in a translator's note, but I don't think that's really necessary; in this situation I would just tacitly correct it.

For Ley, either "Law" or "Act" can be used; some prefer one, some the other. Just "also" is enought for "Asimismo" here, and "is applicable" and "applies" would both be correct; you can use whichever you prefer.