505s can be either basic (second indicator blank), with all contents in a single subfield $$a, or enhanced (second indicator 0), with contents encoded using subfields $$t, $$r, and $$g. When producing original records, create enhanced 505 notes whenever possible. Basic 505 notes are abundant in existing records; there is no obligation to enhance them.
Catalogers may encounter older records in which the 505 is divided into two or more fields, with first indicator 0 for the first 505 field, and first indicator 8 for the subsequent 505 field(s). This practice owed to a 2000-character limit per MARC field in Aleph, Alma's predecessor. In Alma, no such limit applies, and newly-created 505 notes should be kept to a single field (caveat: It has been noted in Alma that a long list of contents -- more than 15 titles? -- in a single 505 field automatically generates extra subfield "a,: creating an error message when attempting to save the record; this can be resolved by simply removing the extra subfield).
Supplied information should be in the language of the manifestation. See RDA 2.3.2.11: "Use the language and script appropriate to the content of the resource being described, except where instructed to use specific terminology"; and the LC-PCC PS Alternative: "Devise a title in a language and script preferred by the agency preparing the description." The Rare Book Section interprets these instructions to mean that the language of the manifestation is preferable.