设置中缺少键盘布局linux

我在 Linux 上使用美国默认键盘，但有时需要德语特殊字符。我在添加了字符的文件夹中制作了自己的文件版本us。usr/share/X11/xkb/symbols这有效，但总是在有更新时被覆盖。

我看到文件中有一个“德国、瑞典和芬兰（美国）”（de_se_fi）布局us。所以我想我会尝试那个。但是，我在设置中找不到任何美式键盘的“德语”变体来选择它们。

更新

我发现它可能在 中丢失usr/share/X11/xkb/rules/base.lst，所以我尝试添加它：

这些是中的行usr/share/X11/xkb/symbols/us：

// German and Swedish characters added as third level symbols to the US keyboard layout
// Author: Stephan Lachnit <[email protected]>, 2019
// the german umlauts are placed over the characters without diaeresis, the sharp-s over the s
// the swedish ao is placed over the p, since it's closed to the position on a swedish keyboard
// the euro sign is placed over the e, as it is usual for german and swedish keyboards
partial alphanumeric_keys
xkb_symbols "de_se_fi"  {

    include "us(basic)"
    include "eurosign(e)"
    name[Group1] = "German, Swedish and Finnish (US)";

    key <AC01> {[ a,            A,          adiaeresis, Adiaeresis ]};
    key <AC02> {[ s,            S,          ssharp,     U1E9E      ]};
    key <AD01> {[ q,            Q,          at                     ]};
    key <AD07> {[ u,            U,          udiaeresis, Udiaeresis ]};
    key <AD09> {[ o,            O,          odiaeresis, Odiaeresis ]};
    key <AD10> {[ p,            P,          aring,      Aring      ]};
    key <AD12> {[ bracketright, braceright, asciitilde             ]};

    include "level3(ralt_switch)"
};

我将此行添加到base.lst（在该! variant部分下）：

  de_se_fi        us: German, Swedish and Finnish (US)

我还尝试创建自己的布局usr/share/X11/xkb/symbols/cust_us_de：

default  partial alphanumeric_keys modifier_keys
xkb_symbols "basic" {

    name[Group1]= "Custom US/DE Keyboard Layout";

    include "us(basic)";
    include "eurosign(e)";

    key <AC01> {[ a,            A,          adiaeresis, Adiaeresis ]};
    key <AC02> {[ s,            S,          ssharp,     U1E9E      ]};
    key <AD07> {[ u,            U,          udiaeresis, Udiaeresis ]};
    key <AD09> {[ o,            O,          odiaeresis, Odiaeresis ]};
};

并将这一行添加到base.lst（在该! layout部分下）：

  cust_us_de      Custom US/DE Keyboard Layout

当我在“设置” → “键盘” → “输入源”中查找它们时，两者都没有出现（重启后也不出现）

有没有办法测试布局文件（例如usr/share/X11/xkb/symbols/cust_us_de）是否正常工作或导致错误？或者一种查看base.lst实际加载了哪些布局/变体的方法？

在编辑上述文件之一后，我是否需要重新启动或进行其他操作才能进行更改？还是关闭和打开设置对话框就足够了？

系统：Manjaro Gnome (wayland)