Regarding Gondborough Rail Group:
I advise you to sort your trains by 'profit last year' in ascending order, and see why they are making you lose money. For example, Train 3 cannot enter its destination station because the destination station is not electrified. You should use 'convert rail' on the station as well.
Train 17 is not profitable because the factory from which it's supposed to pick up goods doesn't produce anything; the farm from which the factory was being supplied has closed down. You should pay attention do closing industries
Train 117 and its buddies: you are running way too many trains on that line. I suggest you to sell some of them or make them shorter.
The same thing applies to Train 118 and its group, and there may be some other overloaded lines as well.
Train 164 and its group: there are some un-electrified parts in the line. I think a good strategy for electrifying is to simply drag as large as you can, basically electrifying the whole map. Of course if you don't want to keep some un-electrified tracks for eyecandy or financial reasons.
You still have steamers in 2003 which are ages old. You shouldn't be using models which are no longer available, because their reliabilitl drops very suddenly and they break down really often (even more so because the amount of breakdowns is 'normal' in your settings which is actually the highest). And you should also replace trains when they get old, because old vehicles break down way more. They can't even get to their destination without breaking down 10's of times. If you like your steamers and don't like the fact that they're unavailable after a certain date, consider enabling 'vehicles never expire' in the Advanced Settings.
So I advise you to sell your unprofitable and/or old trains immediately, even by building a depot just in front of them if they can't get to the depot because of the breakdowns
See why your trains are unprofitable and try to repair the situation. You may consider stopping all your vehicles (using the little red dot/flag in the Trains / Road vehicles window) so you won't lose your money fast. 6 million pounds should be able to save your company, although I'm not used to playing with inflation enabled...
P.S.: I advise you not to buy your bankrupt competitors in a situation like this. They went bankrupt for a reason, and you're taking their unprofitable assets which you may get confused in.
EDIT: Breakdowns seem to be the problem in your other game as well. You might consider the obvious solution of lowering the amount of breakdowns or disabling them altogether. Or if you want to keep it this way, you must pay more attention to the maintenance of your vehicles, most importantly by replacing your old locomotives. And I see you make them go to servicing if their reliability drops below 80%. I don't know if it's an efficient strategy, I haven't done it like this yet. I usually enable the flag 'service if needed' on my depot orders, so that they will skip that order id they have been recently serviced. This basically does the same thing as you but it may be a bit better. Or you can make them go to the depot on every trip (even multiple times) if they break down too much.
For trainsets, see the UK Renewal Train Set (UKRS), the North American Renewal Set (NARS) or the 2cc Trainset if you want some more real-life locomotives. Of course there are some more really good NewGRFs out there, this post
is quite a good summary of some popular NewGRFs. But beware, some of these train sets have really high running costs...