The ZHA “map” shows all discovered routes between devices, not just the ones it’s actually using. From the colours, it looks as if there is only one error-free connection to the coordinator (the one going downwards), so most of the traffic will be going that way. If you’re happy with the LoraTap, I would add a couple more near the coordinator. (They’re not really “extenders”, by the way, in the wi-fi sense. Their function is to make the mesh denser so there are more possible routes for messages to take.)
You might also try checking how much noise there is on the channel you are using. Finding a channel that doesn’t clash with wi-fi can improve any Zigbee network. There’s a good blog post on choosing a channel here.
With ZHA you can check channels by going to the ZHA card in Devices & Services, clicking on the three dots next to Configure and selecting Download diagnostics. Right at the end of the file you get will be something like this:
"energy_scan": {
"11": 73.50699819621309,
"12": 3.2311094587038967,
"13": 70.89933442360993,
"14": 91.05606689948522,
"15": 85.82097888710312,
"16": 65.26028270288712,
"17": 7.659755505061292,
"18": 43.057636198227904,
"19": 1.1664179210724432,
"20": 62.257682586134884,
"21": 2.509919386096536,
"22": 3.6632469452765037,
"23": 4.15070068297423,
"24": 0.9017765778954641,
"25": 1.5075412082833717,
"26": 21.09014924761344
The percentages show the amount of noise on each one, including Zigbee traffic, wi-fi traffic (your neighbour’s as well as yours) and other interference.
Edit: I assume you’re following all the advice about putting the SkyConnect on the end of a long USB cable etc. There’s lots of good stuff here: