Try to stick to written contact, so I can use google translation, otherwise I call Booking.com and they usually can assist, as many of their people are bilingual and can reach out to the guests even more than we can, also if they can’t get anywhere they will advise you on what to do to cover yourself. They are very helpful, and there to assist us, as when we are successful they benefit, vice versa!
I have a check in time that suits me. 6-10pm. Then if I can’t be there I make sure someone is. I also send confirmation e mail and text and WhatsApp, if I see that, as it’s free, as soon as I see they’ve booked so I can catch them hopefully still on line, requesting a text from them when on way or an eta, so I can ensure somebody is at the property to give them access, and this wording usually makes them more attentive! Although of course there are times when guests cannot be contacted but you’ve covered yourself if somebody’s available during times you’ve stated.