您没有正确设置关联

TeamsTable.php

$this->hasMany('MatchSchedulesA', [
    'foreignKey' => 'team_a',
    'className' => 'MatchSchedules'
]);
$this->hasMany('MatchSchedulesB', [
    'foreignKey' => 'team_b',
    'className' => 'MatchSchedules'
]);

在MatchSchedulesTable.php中

$this->belongsTo('TeamsA', [
    'foreignKey' => 'team_a',
    'joinType' => 'INNER',
    'className' => 'Teams'
]);
$this->belongsTo('TeamsB', [
    'foreignKey' => 'team_b',
    'joinType' => 'INNER',
    'className' => 'Teams'
]);

和

$matches = $this->MatchSchedules->find('all', [
  'contain' => [
      'TeamsA',
      'TeamsB
  ]
]);

很高兴您重新命名：

MatchSchedulesA to HomeMatches 
MatchSchedulesB to GuestMatches 
team_a to home_team 
team_b to guest_team 
TeamsA to HomeTeams 
TeamsB to GuestTeams