Errr... I would say... 70-80% and above whenever possible? Just try your best to get the highest readings while positioning your antenna.

And make sure the BER is always 0.00 (Bit Error Rate) and it's not fluctuating. MYTV box does indicate that on the diagnosis page. When BER is 0, that means the reception doesn't have signal errors (stable signal), hence you won't experience pixelation or intermittent loss of signal.

Oh, I wasn't aware the BER reading on your previous photos, and plus you edited the post by adding more photos (Lowyat forum didn't notify me  ) Then I have some corrections to made...
And wah, that "hobby grade splicing" Confirm reduce signal... Use a cable splitter, like this...

https://shopee.com.my/2way-splitter-for-rg6...5202.2851272280

Pre BER means the readings of any data errors receive by your MYTV, before it is being corrected.
Post BER means the result after the receiver (MYTV box) corrected the data signal errors received earlier.

Anyhow, both pre and post BER should be 0.00

BER of 1 and 2 may be acceptable and may able to watch as usual, but susceptible to viewing disruption at anytime since the signal is not stable.
Because BER means "bit error rate", that means the "data" has errors for some reasons (e.g. cable attenuation, interference, weak signal). So that's why the BER should be 0.00, or else you will experience intermittent disruption in reception.

I think you can get started, firstly by removing that tape on the cables used by your landlord's "hobby grade splicing" and re-terminate the cable with F connectors, then connect to the cable splitter. I don't think your landlord would mind that la.... Even if your landlord is not friendly type, I don't think he/she would mind also, since using proper cable splitter will be better than that "hobby splicing" method.

And once you did that, and the signal improves and BER is 0.00, both TVs also no signal issue, then no need to get new antenna and cable... 
In that case, signal quality and BER matters more than signal strength. Simply means, just because you have strong signal, doesn't mean you have good signal.

yongtjunkit
The VHF part of antenna looks broken and the dangling cable is supposed to be connected from the UHF section box to the VHF section which supposed to have another box. Since the VHF section is disconnected, there may be impedance matching issues at the open ended cable.
The other issue is the poor splitting to two TVs without a proper splitter. This too will cause impedance matching issues as a proper splitter will have a transformer in it.
A mismatched impedance will cause signal loss/degradation and signal reflection within the antenna cable.

So, avoid Botato then?
It's the cheapest while Pensonic is over three times more expensive.

Does it support HbbTV feature for pressing red button to access interactive features like news, weather, EPG and VOD on rtm channels and TV3?

The EPG data you get, is from DVB-T2.
The broadcaster also pays MYTV Broadcasting to provide EPG data to viewers, as overall the EPG data also uses about 1-2Mbps (that includes 7 days EPG, programme description, etc.) Astro also same.

So, don't think that MYTV Broadcasting is so kind to give you EPG data. Broadcaster also have to pay them money for that too, so whether that channel has EPG data or not, is also depends on that broadcaster too.

You can use the generic USB WiFi adapter.. Not necessarily must use the one that come with it. I mean generic, it could be those no brand type, cheap RM10-15 type, 802.11n 150MHz type. Those usually can work already.

yongtjunkit
The VHF part of antenna looks broken and the dangling cable is supposed to be connected from the UHF section box to the VHF section which supposed to have another box. Since the VHF section is disconnected, there may be impedance matching issues at the open ended cable.
The other issue is the poor splitting to two TVs without a proper splitter. This too will cause impedance matching issues as a proper splitter will have a transformer in it.
A mismatched impedance will cause signal loss/degradation and signal reflection within the antenna cable.

Ya DVB-T2 also got EPG but the channels have their own EPG with their own design via HbbTV too. Sometimes the DVB-T2 EPG is missing for some channels then can use the HbbTV EPG.

What's important to me is the reliability and quality of playback.
Are they all of the same video quality?

The MYTV Advance STB is also kinda laggy and gets hot. The recording feature also doesn't work. It has Ethernet port so can access HbbTV but the HbbTV is laggy till VOD can hardly be played.

Using a TV with built-in DVB-T2 and HbbTV support works way better.

Anyone using the given free MyFreeview decoder (forgot its model name)?
Any particular reason to connect to the Wifi?

1. It never use the internet to sync time.
2. Hbbtv probably not support for free / standard decoder version.
3. What kind of ancient Wifi protocol is using? The input password not even support for symbol characters (eg @).

Anyone using the DVB-T2 U-002?
Where to find the firware update for this model?
I can open video from the pendrive but no sound.
Plan to see if got any update to support video codec or had better UI~

More space on Mux 2, since 114 & 121 relocated to RTM mux (aka gov mux).

My goodness... Another common problem in "those" Malaysian made website.
http://status.mytvbroadcasting.my/

A website, that user were to enter and submit IC number, is not HTPPS.
The website, is in HTTP instead of HTTPS.
Imagine that users have to enter own IC number into an unsecured website.      
Those who don't know what is HTTP and HTTPS, you may Google search that on your own.

https://sayasukamyfreeview.com/?lang=ms
This one appears to be HTTPS, but as I checked, it's not fully HTTPS, so it is not fully secure.

I don't think MYTV customer service would even understand what does this mean.
Such cases like this, who should I refer to convey this complaint?

That's a very good sign.
What's the area again? And what's the approx distance from nearest transmitter again? For your both uncle and aunt's hse...

Eiiii so near only...
That antenna you bought good enough ady...
Just find a suitable spot to place it permanently. If don't feel like drilling the wall, then just put it anywhere you want, like on top of cabinet or something.

Eiiii so near only...
That antenna you bought good enough ady...
Just find a suitable spot to place it permanently. If don't feel like drilling the wall, then just put it anywhere you want, like on top of cabinet or something.