Some UAs which look to be mobile ones are not recognized

[DaimonPl]

Not 100% sure about those, but looks to be mobile:

Mobile Safari

• Opera/9.80 (Windows NT 5.1; Opera Mobi/46154) Presto/2.11.355 Version/12.10
• Opera/9.80 (J2ME/MIDP; Opera Mini; U; en) Presto/2.12.423 Version/12.16
• Opera/9.80 (J2ME/MIDP; Opera Mini; U; ru) Presto/2.12.423 Version/12.16
• Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) 38.0.2125.102 Mobile Safari/537.36
• Opera/9.7 (WindowsMobile; PPC; Opera Mobi/35267; U; en; Presto/2.1.1)
• Mozilla/5.0 (Linux; Android 4.3; Spider Build/JLS36C) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2860.0 Mobile Safari/537.36
• Opera/9.80 (Linux; Opera Mobi/2; U; ru) Presto/2.10.254 Version/12.00
• Opera/9.80 (Windows NT 5.1; U; Opera Mobi; en-GB; CEB-42)
• Mozilla/5.0 (Opera/9.80; Windows NT 6.1 U; en-EN ) AppleWebKit/535.1 (KHTML, like Gecko) Version/12.00/.. Mobile Safari/535.1

[Findus23]

They all seem to work for me. What exactly are you missing?

Opera/9.80 (Windows NT 5.1; Opera Mobi/46154) Presto/2.11.355 Version/12.10:
[
    {
        "type": "browser",
        "name": "Opera Mobile",
        "short_name": "OM",
        "version": "12.10",
        "engine": "Presto",
        "engine_version": "2.11.355"
    },
    {
        "name": "Windows",
        "short_name": "WIN",
        "version": "XP",
        "platform": ""
    }
]
Opera/9.80 (J2ME/MIDP; Opera Mini; U; en) Presto/2.12.423 Version/12.16:
[
    {
        "type": "browser",
        "name": "Opera",
        "short_name": "OP",
        "version": "12.16",
        "engine": "Presto",
        "engine_version": "2.12.423"
    },
    []
]
Opera/9.80 (J2ME/MIDP; Opera Mini; U; ru) Presto/2.12.423 Version/12.16:
[
    {
        "type": "browser",
        "name": "Opera",
        "short_name": "OP",
        "version": "12.16",
        "engine": "Presto",
        "engine_version": "2.12.423"
    },
    []
]
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) 38.0.2125.102 Mobile Safari/537.36:
[
    {
        "type": "browser",
        "name": "Safari",
        "short_name": "SF",
        "version": "",
        "engine": "WebKit",
        "engine_version": "537.36"
    },
    {
        "name": "GNU\/Linux",
        "short_name": "LIN",
        "version": "",
        "platform": "x64"
    }
]
Opera/9.7 (WindowsMobile; PPC; Opera Mobi/35267; U; en; Presto/2.1.1):
[
    {
        "type": "browser",
        "name": "Opera",
        "short_name": "OP",
        "version": "9.7",
        "engine": "Presto",
        "engine_version": "2.1.1"
    },
    {
        "name": "Windows",
        "short_name": "WIN",
        "version": "",
        "platform": ""
    }
]
Opera/9.80 (Linux; Opera Mobi/2; U; ru) Presto/2.10.254 Version/12.00:
[
    {
        "type": "browser",
        "name": "Opera Mobile",
        "short_name": "OM",
        "version": "12.00",
        "engine": "Presto",
        "engine_version": "2.10.254"
    },
    {
        "name": "GNU\/Linux",
        "short_name": "LIN",
        "version": "",
        "platform": ""
    }
]
Opera/9.80 (Windows NT 5.1; U; Opera Mobi; en-GB; CEB-42):
[
    {
        "type": "browser",
        "name": "Opera",
        "short_name": "OP",
        "version": "9.80",
        "engine": "Presto",
        "engine_version": ""
    },
    {
        "name": "Windows",
        "short_name": "WIN",
        "version": "XP",
        "platform": ""
    }
]
Mozilla/5.0 (Opera/9.80; Windows NT 6.1 U; en-EN ) AppleWebKit/535.1 (KHTML, like Gecko) Version/12.00/.. Mobile Safari/535.1:
[
    {
        "type": "browser",
        "name": "Opera",
        "short_name": "OP",
        "version": "12.00",
        "engine": "Presto",
        "engine_version": ""
    },
    {
        "name": "Windows",
        "short_name": "WIN",
        "version": "7",
        "platform": ""
    }
]```

[sgiehl]

Guess he means that they are maybe detected as desktop device and not as smartphone or similar

[DaimonPl]

Yep,

If I remember correctly is_mobile did not have "true" value for those

[Findus23]

Indeed, for all of them is_mobile returns false.
I have missed that.