I see that you have run into the sometimes 'aggressive' advice that is quite often available here
Other people have given you the correct terminology to use, so I won't address that.
I will give you some advice that you haven't asked for, this will be based on my experiences and will totally ignore your situation and experience, cause I don't know what that is.
I have been in your situation, more or less, a lot of work to do but no time to do it properly, but it has to be done. I tried to get a local company to do it for me, but they kept quoting for things I didn't want, this has happened with different projects, PA work, website work, design work. Fairly small jobs but the supplier kept trying to build their part, and the costs were way higher than I had hoped. During a meeting with one of them he said that he wouldn't do the work himself but his team on Freelancer would do it for him. (Freelancer is now upwork) So I thought to myself that if using a local company was going to get it sent to a freelancer anyway why shouldn't I organise it myself, more direct control and less money (a lot less money). Anyway it worked out really well.
So I would advise you to go onto upwork, open an account, and put up a test job for maybe half a dozen images and see what comes of it, it will cost you a few pounds but might save a fortune and a load of time and grief.
Of course the down side is that it might be a disaster

and dealing with the initial applications could be a nightmare. I would recommend that you put in some sort of test in the job description to weed out the people who haven't bothered to read the job description. I put a line in it somewhere saying "Put the word 'Balloon' into the first line of your reply", I find that two thirds of people don't do that and get excluded right away.
Most of the people I have dealt with can read/write excellent English and I belive most can speak English pretty well. You can communicate with them via message board, email and if you like by video conferencing (I never used that). You can pay based on an hourly rate or a per item/job rate etc
I feel that it is a really good system, not without issues, but pretty good, and for me easier than trying to do it myself, or sourcing locally.
I will be putting up a job soon where I will direct someone to a website and ask them to extract about 50 odd images and then do a little bit of work on them and send to me. I will be able to organise in under 30 mins and i'd be surprised if it will cost more than £25, but to do it myself would probably be 10plus hours spread out over a week or more.
Anyway, treat this advice like you got it off some guy on the internet.
Good Luck
Jim