I understand the differences between aspectual and modal particle, but I have some confusion about when a sentence ends with a 了 and at the same time with a verb, like 来了. So it is aspectual or modal?
“来” is an action. So it is aspectual. It indicates the action has ended.
“来” is not a situation. Although a situation that "I am here" can be inferred from the fact that the action of coming (来) has ended. So it is not an indication of new situation.
You can say "我在了", in which the "了" is modal. "在" here indicates a (new) situation.
来了 gives no information about time. That information comes from other words.
- 她十有八九不会来了。不会 = will not
- 我父母昨天来了。 昨天 = yesterday
- 他不再来了。 不再 = never again, not anymore
- 他被吸引到外面来了。 到 ... 来 = to ... from
- 夜凉了，秋天快要来了。 快要 = soon will
- 我们的周年纪念又来了。 又 = again, soon
- 冬天来了，春天还会远吗？ 冬天来了 = if winter comes (subjunctive) "Ode to the West Wind, Shelley"
- 我想她很快就会来了。 会来了 = will come
"我父母来了。" says Mum and Dad arrived, but you don't know when!