That sounds like a great project - and if it works it should be very rewarding! 
If I may, I’d like to draw three scenarios for you. #1 is the easy, but not very suitable/adapted way by using IR commands (not recommended), #2 would be to use the integration for WebOS (better, but not my favourite), where #3 would be some kind of ultimate solution for your GF (this is, what I’d do).
#1 IR
I wouldn’t recommend that, as it is a uni-directional way of communication, that is by definition error prone. And it offers no benefit at all, at least not for your GF, as she still isn’t the “master of the TV”, but just a participant in a guessing game. If this is really the way you want to go (after reading the alternatives down below), please tell us, so we can go deeper into this and explain it further.
#2 LG WebOS integration
This one is a robust solution, where you can achieve most things you want to. The advantage of this solution is the bidirectional communication that is made with an integration into HA. If you send a command, you will immediately get back a result to HA, so HA knows what state the TV is in, which level for volume is set and a lot of other things, one could need to make an informed decision.
It is as well a better solution compared to IR, as you can react on things, that happen on your TV, which you can’t with only just IR, simply because you have no back channel from your TV to HA.
#3 Introducing Rhasspy voice assistant
This is, IMHO, the best solution, as it is a combination of the WebOS integration, combined with a local voice assistant, that get’s the hard work done for your GF. After a little training (don’t worry, nothing fancy and no sports equipment needed 
), Rhasspy can do the heavy lifting of getting the idea what is wanted from the TV and translates/transforms this intention to an automation, that is run by HA and will control and change your TV settings.
Let me give you an example: If your GF wants to swith to a specific channel, she’s just telling the TV: “Rhasspy, switch to BBC” or “Rhasspy, turn up the volume by two points”. But the real fun comes with custom commands, that save time and nerves, like “Rhasspy, I want to watch “Desperate Housewives” on Amazon”.
This is the point, where you can’t go with Google, as it is a PITA to learn and control all the various wishes one can have. And it let’s you control what is happening, and not Google guessing, what should happen. I know, I know, Google gives a cheap and for most cases very good possibility to use a voice assistant, but if you want a lot more control (and therefor the possibility to customize this experience) over your voice assitant, I’d highly recommend Rhasspy!
Wichever way you choose, in the end it is running an automation in HA, that changes things the way you like. So taking your example, it would be something like this in the action part of your automation:
action:
- service: webostv.turn_on
entity_id: media_player.lg_tv_livingroom
- delay: '00:00:03'
- service: webostv.button
target:
entity_id: media_player.lg_tv_livingroom
data:
button: 'ENTER'
- delay: '00:00:03'
- repeat:
count: 3
sequence:
- service: webostv.button
target:
entity_id: media_player.lg_tv_livingroom
data:
button: 'DOWN'
- delay: '00:00:01'
- service: webostv.button
target:
entity_id: media_player.lg_tv_livingroom
data:
button: 'ENTER'
Depending on the way you choose, this most likely can be shortened, at least the delay can be left out, as the TV should understand commands, that are sent after one another. No need for a delay. And in regard to the documentation of the LG WebOS integration, you can simplify this by sending the direct command for what you want to achieve, like “Switch to channel 1” and just use this:
service: media_player.play_media
target:
entity_id: media_player.lg_webos_smart_tv
data:
media_content_id: 1
media_content_type: "channel"
You see, with the integration (and maybe Rhasspy as well), you can build a very intuitive way, to control the TV and make your GF happy (and down the road yourself).
Hope this helps in deciding which way to go.
thanks again!