Added it, though this shouldn't pose a typescript error, just no autocomplete:

export interface CollectionFieldSchema {
  name: string;
  type: FieldType;
  optional?: boolean;
  facet?: boolean;
  index?: boolean;
  sort?: boolean;
  locale?: string;
  infix?: boolean;
  stem?: boolean;
  num_dim?: number;
  store?: boolean;
  range_index?: boolean; // even if missing the next one will take care of it
  [t: string]: unknown; // this just says that it's a Record<string, unknown>, so anything with a key of string goes
}